Method for measuring channel state information in unlicensed band, and apparatus therefor

ABSTRACT

A method by which a terminal measures channel state information (CSI) in an unlicensed band is disclosed. Particularly, the method comprises: receiving at least one channel state information-reference signal (CSI-RS) through at least one listen before talk (LBT) sub-band of a plurality of LBT sub-bands for transmitting a plurality of CSI-RSs within one transmit opportunity (TxOP) section; determining each measurement use for at least one CSI-RS; and measuring the CSI on the basis of each measurement use for the at least one determined CSI-RS, wherein the determination of each measurement use for the at least one CSI-RS is the determining of whether the CSI-RS is for an interference measurement or the CSI-RS is for a signal measurement.

TECHNICAL FIELD

The present disclosure relates to a method and apparatus for measuringchannel state information (CSI) in an unlicensed band, and moreparticularly, to a method and apparatus for measuring CSI, when achannel state information-reference signal (CSI-RS) is transmitted inunits of a subband in an unlicensed band.

BACKGROUND ART

As more and more communication devices demand larger communicationtraffic along with the current trends, a future-generation 5thgeneration (5G) system is required to provide an enhanced wirelessbroadband communication, compared to the legacy LTE system. In thefuture-generation 5G system, communication scenarios are divided intoenhanced mobile broadband (eMBB), ultra-reliability and low-latencycommunication (URLLC), massive machine-type communication (mMTC), and soon.

Herein, eMBB is a future-generation mobile communication scenariocharacterized by high spectral efficiency, high user experienced datarate, and high peak data rate, URLLC is a future-generation mobilecommunication scenario characterized by ultra-high reliability,ultra-low latency, and ultra-high availability (e.g., vehicle toeverything (V2X), emergency service, and remote control), and mMTC is afuture-generation mobile communication scenario characterized by lowcost, low energy, short packet, and massive connectivity (e.g., Internetof things (IoT)).

DISCLOSURE Technical Problem

The present disclosure is intended to provide a method and apparatus formeasuring channel state information (CSI) in an unlicensed band.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

Technical Solution

According to an embodiment of the present disclosure, a method ofmeasuring channel state information (CSI) in an unlicensed band by auser equipment (UE) may include receiving at least one channel stateinformation-reference signal (CSI-RS) in at least one of a plurality oflisten-before-talk (LBT) subbands for transmission of a plurality ofCSI-RSs in one transmission opportunity (TxOP) duration, determining ameasurement purpose of each of the at least one CSI-RS, and measuringCSI based on the determined measurement purpose of each of the at leastone CSI-RS. The determination of a measurement purpose of each of the atleast one CSI-RS may include determining whether each of the at leastone CSI-RS is a CSI-RS for interference measurement or a CSI-RS forsignal measurement.

Based on the at least one CSI-RS including none of the CSI-RS forinterference measurement and the CSI-RS for signal measurement, CSI maynot be measured.

The method may further include receiving information for measuring oneof the CSI-RS for interference measurement and the CSI-RS for signalmeasurement. The measurement of CSI may include measuring the CSI basedon the at least one CSI-RS being the one CSI-RS or not measuring the CSIbased on the at least one CSI-RS not being the one CSI-RS.

Further, the one TxOP duration may be a TxOP duration closest to a timeof measuring the CSI among a plurality of TxOP durations.

Further, the at least one CSI-RS may be a non-zero-power (NZP) CSI-RS.

Further, a resource area for a zero-power (ZP) CSI-RS may be identicalto a resource area for the NZP CSI-RS.

Further, the UE may be communicable with at least one of another UE, anetwork, a base station (BS), or an autonomous driving vehicle.

According to the present disclosure, a UE for measuring CSI in anunlicensed band may include at least one transceiver, at least oneprocessor, and at least one memory operatively coupled to the at leastone processor and storing instructions which when executed, cause the atleast one processor to perform specific operations. The specificoperations may include receiving, through the at least one transceiver,at least one CSI-RS in at least one of a plurality of LBT subbands fortransmission of a plurality of CSI-RSs in one TxOP duration, determininga measurement purpose of each of the at least one CSI-RS, and measuringCSI based on the determined measurement purpose of each of the at leastone CSI-RS. The determination of a measurement purpose of each of the atleast one CSI-RS may include determining whether each of the at leastone CSI-RS is a CSI-RS for interference measurement or a CSI-RS forsignal measurement.

Based on the at least one CSI-RS including none of the CSI-RS forinterference measurement and the CSI-RS for signal measurement, CSI maynot be measured.

Further, the specific operations may further include receivinginformation for measuring one of the CSI-RS for interference measurementand the CSI-RS for signal measurement. The measurement of CSI mayinclude measuring the CSI based on the at least one CSI-RS being the oneCSI-RS or not measuring the CSI based on the at least one CSI-RS notbeing the one CSI-RS.

Further, the one TxOP duration may be a TxOP duration closest to a timeof measuring the CSI among a plurality of TxOP durations.

Further, the at least one CSI-RS may be an NZP CSI-RS.

Further, a resource area for a ZP CSI-RS may be identical to a resourcearea for the NZP CSI-RS.

Further, the UE may be communicable with at least one of another UE, anetwork, a base station (BS), or an autonomous driving vehicle.

According to an embodiment of the present disclosure, an apparatus formeasuring CSI in an unlicensed band may include at least one processor,and at least one memory operatively coupled to the at least oneprocessor and storing instructions which when executed, cause the atleast one processor to perform specific operations. The specificoperations may include receiving, through the at least one transceiver,at least one CSI-RS in at least one of a plurality of LBT subbands fortransmission of a plurality of CSI-RSs in one TxOP duration, determininga measurement purpose of each of the at least one CSI-RS, and measuringCSI based on the determined measurement purpose of each of the at leastone CSI-RS. The determination of a measurement purpose of each of the atleast one CSI-RS may include determining whether each of the at leastone CSI-RS is a CSI-RS for interference measurement or a CSI-RS forsignal measurement.

Advantageous Effects

According to the present disclosure, even when a channel stateinformation-reference signal (CSI-RS) is transmitted in units of asubband, CSI for a whole CSI-RS band may be efficiently acquired.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present disclosure are not limited to whathas been particularly described hereinabove and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the control-plane and user-planearchitecture of radio interface protocols between a user equipment (UE)and an evolved UMTS terrestrial radio access network (E-UTRAN) inconformance to a 3rd generation partnership project (3GPP) radio accessnetwork standard.

FIG. 2 is a diagram illustrating physical channels and a general signaltransmission method using the physical channels in a 3GPP system.

FIGS. 3, 4 and 5 are diagrams illustrating structures of a radio frameand slots used in a new RAT (NR) system.

FIGS. 6, 7 and 8 are diagrams illustrating UL/DL transmission in anunlicensed band.

FIG. 9 is a diagram illustrating analog beamforming in the NR system.

FIGS. 10, 11, 12, 13, and 14 are diagrams illustrating beam managementin the NR system.

FIG. 15 is a diagram illustrating a signal flow for channel stateinformation (CSI) reporting.

FIGS. 16, 17, and 18 are diagrams illustrating a physical downlinkcontrol channel (PDCCH) in the NR system.

FIG. 19 is a diagram illustrating an embodiment of a discontinuousreception (DRX) operation.

FIG. 20 is a diagram illustrating an implementation example of channelstate information-reference signal (CSI-RS) transmission in anunlicensed band.

FIGS. 21, 22 and 23 are diagrams illustrating an implementation exampleof operations of a UE, a base station (BS), and a network according toan embodiment of the present disclosure.

FIG. 24 is a diagram illustrating a method of updating CSI according toan embodiment of the present disclosure.

FIG. 25 illustrates an example of a communication system to whichembodiments of the present disclosure are applied.

FIGS. 26 to 28 illustrate examples of various wireless devices to whichembodiments of the present disclosure are applied.

FIG. 29 illustrates an exemplary signal processing circuit to whichembodiments of the present disclosure are applied.

BEST MODE

The configuration, operation, and other features of the presentdisclosure will readily be understood with embodiments of the presentdisclosure described with reference to the attached drawings.Embodiments of the present disclosure as set forth herein are examplesin which the technical features of the present disclosure are applied toa 3rd generation partnership project (3GPP) system.

While embodiments of the present disclosure are described in the contextof long term evolution (LTE) and LTE-advanced (LTE-A) systems, they arepurely exemplary. Therefore, the embodiments of the present disclosureare applicable to any other communication system as long as the abovedefinitions are valid for the communication system.

The term, base station (BS) may be used to cover the meanings of termsincluding remote radio head (RRH), evolved Node B (eNB or eNode B),transmission point (TP), reception point (RP), relay, and so on.

The 3GPP communication standards define downlink (DL) physical channelscorresponding to resource elements (REs) carrying information originatedfrom a higher layer, and DL physical signals which are used in thephysical layer and correspond to REs which do not carry informationoriginated from a higher layer. For example, physical downlink sharedchannel (PDSCH), physical broadcast channel (PBCH), physical multicastchannel (PMCH), physical control format indicator channel (PCFICH),physical downlink control channel (PDCCH), and physical hybrid ARQindicator channel (PHICH) are defined as DL physical channels, andreference signals (RSs) and synchronization signals (SSs) are defined asDL physical signals. An RS, also called a pilot signal, is a signal witha predefined special waveform known to both a gNode B (gNB) and a userequipment (UE). For example, cell specific RS, UE-specific RS (UE-RS),positioning RS (PRS), and channel state information RS (CSI-RS) aredefined as DL RSs. The 3GPP LTE/LTE-A standards define uplink (UL)physical channels corresponding to REs carrying information originatedfrom a higher layer, and UL physical signals which are used in thephysical layer and correspond to REs which do not carry informationoriginated from a higher layer. For example, physical uplink sharedchannel (PUSCH), physical uplink control channel (PUCCH), and physicalrandom access channel (PRACH) are defined as UL physical channels, and ademodulation reference signal (DMRS) for a UL control/data signal, and asounding reference signal (SRS) used for UL channel measurement aredefined as UL physical signals.

In the present disclosure, the PDCCH/PCFICH/PHICH/PDSCH refers to a setof time-frequency resources or a set of REs, which carry downlinkcontrol information (DCI)/a control format indicator (CFI)/a DLacknowledgement/negative acknowledgement (ACK/NACK)/DL data. Further,the PUCCH/PUSCH/PRACH refers to a set of time-frequency resources or aset of REs, which carry UL control information (UCI)/UL data/a randomaccess signal. In the present disclosure, particularly a time-frequencyresource or an RE which is allocated to or belongs to thePDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH is referred to as a PDCCHRE/PCFICH RE/PHICH RE/PDSCH RE/PUCCH RE/PUSCH RE/PRACH RE or a PDCCHresource/PCFICH resource/PHICH resource/PDSCH resource/PUCCHresource/PUSCH resource/PRACH resource. Hereinbelow, if it is said thata UE transmits a PUCCH/PUSCH/PRACH, this means that UCI/UL data/a randomaccess signal is transmitted on or through the PUCCH/PUSCH/PRACH.Further, if it is said that a gNB transmits a PDCCH/PCFICH/PHICH/PDSCH,this means that DCI/control information is transmitted on or through thePDCCH/PCFICH/PHICH/PDSCH.

Hereinbelow, an orthogonal frequency division multiplexing (OFDM)symbol/carrier/subcarrier/RE to which a CRS/DMRS/CSI-RS/SRS/UE-RS isallocated to or for which the CRS/DMRS/CSI-RS/SRS/UE-RS is configured isreferred to as a CRS/DMRS/CSI-RS/SRS/UE-RS symbol/carrier/subcarrier/RE.For example, an OFDM symbol to which a tracking RS (TRS) is allocated orfor which the TRS is configured is referred to as a TRS symbol, asubcarrier to which a TRS is allocated or for which the TRS isconfigured is referred to as a TRS subcarrier, and an RE to which a TRSis allocated or for which the TRS is configured is referred to as a TRSRE. Further, a subframe configured to transmit a TRS is referred to as aTRS subframe. Further, a subframe carrying a broadcast signal isreferred to as a broadcast subframe or a PBCH subframe, and a subframecarrying a synchronization signal (SS) (e.g., a primary synchronizationsignal (PSS) and/or a secondary synchronization signal (SSS)) isreferred to as an SS subframe or a PSS/SSS subframe. An OFDMsymbol/subcarrier/RE to which a PSS/SSS is allocated or for which thePSS/SSS is configured is referred to as a PSS/SSS symbol/subcarrier/RE.

In the present disclosure, a CRS port, a UE-RS port, a CSI-RS port, anda TRS port refer to an antenna port configured to transmit a CRS, anantenna port configured to transmit a UE-RS, an antenna port configuredto transmit a CSI-RS, and an antenna port configured to transmit a TRS,respectively. Antenna port configured to transmit CRSs may bedistinguished from each other by the positions of REs occupied by theCRSs according to CRS ports, antenna ports configured to transmit UE-RSsmay be distinguished from each other by the positions of REs occupied bythe UE-RSs according to UE-RS ports, and antenna ports configured totransmit CSI-RSs may be distinguished from each other by the positionsof REs occupied by the CSI-RSs according to CSI-RS ports. Therefore, theterm CRS/UE-RS/CSI-RS/TRS port is also used to refer to a pattern of REsoccupied by a CRS/UE-RS/CSI-RS/TRS in a predetermined resource area.

5G communication involving a new radio access technology (NR) systemwill be described below.

Three key requirement areas of 5G are (1) enhanced mobile broadband(eMBB), (2) massive machine type communication (mMTC), and (3)ultra-reliable and low latency communications (URLLC).

Some use cases may require multiple dimensions for optimization, whileothers may focus only on one key performance indicator (KPI). 5Gsupports such diverse use cases in a flexible and reliable way.

eMBB goes far beyond basic mobile Internet access and covers richinteractive work, media and entertainment applications in the cloud oraugmented reality (AR). Data is one of the key drivers for 5G and in the5G era, we may for the first time see no dedicated voice service. In 5G,voice is expected to be handled as an application program, simply usingdata connectivity provided by a communication system. The main driversfor an increased traffic volume are the increase in the size of contentand the number of applications requiring high data rates. Streamingservices (audio and video), interactive video, and mobile Internetconnectivity will continue to be used more broadly as more devicesconnect to the Internet. Many of these applications require always-onconnectivity to push real time information and notifications to users.Cloud storage and applications are rapidly increasing for mobilecommunication platforms. This is applicable for both work andentertainment. Cloud storage is one particular use case driving thegrowth of uplink data rates. 5G will also be used for remote work in thecloud which, when done with tactile interfaces, requires much lowerend-to-end latencies in order to maintain a good user experience.Entertainment, for example, cloud gaming and video streaming, is anotherkey driver for the increasing need for mobile broadband capacity.Entertainment will be very essential on smart phones and tabletseverywhere, including high mobility environments such as trains, carsand airplanes. Another use case is AR for entertainment and informationsearch, which requires very low latencies and significant instant datavolumes.

One of the most expected 5G use cases is the functionality of activelyconnecting embedded sensors in every field, that is, mMTC. It isexpected that there will be 20.4 billion potential Internet of things(IoT) devices by 2020. In industrial IoT, 5G is one of areas that playkey roles in enabling smart city, asset tracking, smart utility,agriculture, and security infrastructure.

URLLC includes services which will transform industries withultra-reliable/available, low latency links such as remote control ofcritical infrastructure and self-driving vehicles. The level ofreliability and latency are vital to smart-grid control, industrialautomation, robotics, drone control and coordination, and so on.

Now, multiple use cases in a 5G communication system including the NRsystem will be described in detail.

5G may complement fiber-to-the home (FTTH) and cable-based broadband (ordata-over-cable service interface specifications (DOCSIS)) as a means ofproviding streams at data rates of hundreds of megabits per second togiga bits per second. Such a high speed is required for TV broadcasts ator above a resolution of 4K (6K, 8K, and higher) as well as virtualreality (VR) and AR. VR and AR applications mostly include immersivesport games. A special network configuration may be required for aspecific application program. For VR games, for example, game companiesmay have to integrate a core server with an edge network server of anetwork operator in order to minimize latency.

The automotive sector is expected to be a very important new driver for5G, with many use cases for mobile communications for vehicles. Forexample, entertainment for passengers requires simultaneous highcapacity and high mobility mobile broadband, because future users willexpect to continue their good quality connection independent of theirlocation and speed. Other use cases for the automotive sector are ARdashboards. These display overlay information on top of what a driver isseeing through the front window, identifying objects in the dark andtelling the driver about the distances and movements of the objects. Inthe future, wireless modules will enable communication between vehiclesthemselves, information exchange between vehicles and supportinginfrastructure and between vehicles and other connected devices (e.g.,those carried by pedestrians). Safety systems may guide drivers onalternative courses of action to allow them to drive more safely andlower the risks of accidents. The next stage will be remote-controlledor self-driving vehicles. These require very reliable, very fastcommunication between different self-driving vehicles and betweenvehicles and infrastructure. In the future, self-driving vehicles willexecute all driving activities, while drivers are focusing on trafficabnormality elusive to the vehicles themselves. The technicalrequirements for self-driving vehicles call for ultra-low latencies andultra-high reliability, increasing traffic safety to levels humanscannot achieve.

Smart cities and smart homes, often referred to as smart society, willbe embedded with dense wireless sensor networks. Distributed networks ofintelligent sensors will identify conditions for cost- andenergy-efficient maintenance of the city or home. A similar setup can bedone for each home, where temperature sensors, window and heatingcontrollers, burglar alarms, and home appliances are all connectedwirelessly. Many of these sensors are typically characterized by lowdata rate, low power, and low cost, but for example, real time highdefinition (HD) video may be required in some types of devices forsurveillance.

The consumption and distribution of energy, including heat or gas, isbecoming highly decentralized, creating the need for automated controlof a very distributed sensor network. A smart grid interconnects suchsensors, using digital information and communications technology togather and act on information. This information may include informationabout the behaviors of suppliers and consumers, allowing the smart gridto improve the efficiency, reliability, economics and sustainability ofthe production and distribution of fuels such as electricity in anautomated fashion. A smart grid may be seen as another sensor networkwith low delays.

The health sector has many applications that may benefit from mobilecommunications. Communications systems enable telemedicine, whichprovides clinical health care at a distance. It helps eliminate distancebarriers and may improve access to medical services that would often notbe consistently available in distant rural communities. It is also usedto save lives in critical care and emergency situations. Wireless sensornetworks based on mobile communication may provide remote monitoring andsensors for parameters such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly importantfor industrial applications. Wires are expensive to install andmaintain, and the possibility of replacing cables with reconfigurablewireless links is a tempting opportunity for many industries. However,achieving this requires that the wireless connection works with asimilar delay, reliability and capacity as cables and that itsmanagement is simplified. Low delays and very low error probabilitiesare new requirements that need to be addressed with 5G.

Finally, logistics and freight tracking are important use cases formobile communications that enable the tracking of inventory and packageswherever they are by using location-based information systems. Thelogistics and freight tracking use cases typically require lower datarates but need wide coverage and reliable location information.

FIG. 1 illustrates control-plane and user-plane protocol stacks in aradio interface protocol architecture conforming to a 3GPP wirelessaccess network standard between a UE and an evolved UMTS terrestrialradio access network (E-UTRAN). The control plane is a path in which theUE and the E-UTRAN transmit control messages to manage calls, and theuser plane is a path in which data generated from an application layer,for example, voice data or Internet packet data is transmitted.

A physical (PHY) layer at layer 1 (L1) provides information transferservice to its higher layer, a medium access control (MAC) layer. ThePHY layer is connected to the MAC layer via transport channels. Thetransport channels deliver data between the MAC layer and the PHY layer.Data is transmitted on physical channels between the PHY layers of atransmitter and a receiver. The physical channels use time and frequencyas radio resources. Specifically, the physical channels are modulated inorthogonal frequency division multiple access (OFDMA) for downlink (DL)and in single carrier frequency division multiple access (SC-FDMA) foruplink (UL).

The MAC layer at layer 2 (L2) provides service to its higher layer, aradio link control (RLC) layer via logical channels. The RLC layer at L2supports reliable data transmission. RLC functionality may beimplemented in a function block of the MAC layer. A packet dataconvergence protocol (PDCP) layer at L2 performs header compression toreduce the amount of unnecessary control information and thusefficiently transmit Internet protocol (IP) packets such as IP version 4(IPv4) or IP version 6 (IPv6) packets via an air interface having anarrow bandwidth.

A radio resource control (RRC) layer at the lowest part of layer 3 (orL3) is defined only on the control plane. The RRC layer controls logicalchannels, transport channels, and physical channels in relation toconfiguration, reconfiguration, and release of radio bearers. A radiobearer refers to a service provided at L2, for data transmission betweenthe UE and the E-UTRAN. For this purpose, the RRC layers of the UE andthe E-UTRAN exchange RRC messages with each other. If an RRC connectionis established between the UE and the E-UTRAN, the UE is in RRCConnected mode and otherwise, the UE is in RRC Idle mode. A Non-AccessStratum (NAS) layer above the RRC layer performs functions includingsession management and mobility management.

DL transport channels used to deliver data from the E-UTRAN to UEsinclude a broadcast channel (BCH) carrying system information, a pagingchannel (PCH) carrying a paging message, and a shared channel (SCH)carrying user traffic or a control message. DL multicast traffic orcontrol messages or DL broadcast traffic or control messages may betransmitted on a DL SCH or a separately defined DL multicast channel(MCH). UL transport channels used to deliver data from a UE to theE-UTRAN include a random access channel (RACH) carrying an initialcontrol message and a UL SCH carrying user traffic or a control message.Logical channels that are defined above transport channels and mapped tothe transport channels include a broadcast control channel (BCCH), apaging control channel (PCCH), a Common Control Channel (CCCH), amulticast control channel (MCCH), a multicast traffic channel (MTCH),etc.

FIG. 2 illustrates physical channels and a general method fortransmitting signals on the physical channels in the 3GPP system.

Referring to FIG. 2, when a UE is powered on or enters a new cell, theUE performs initial cell search (S201). The initial cell search involvesacquisition of synchronization to an eNB. Specifically, the UEsynchronizes its timing to the eNB and acquires a cell identifier (ID)and other information by receiving a primary synchronization channel(P-SCH) and a secondary synchronization channel (S-SCH) from the eNB.Then the UE may acquire information broadcast in the cell by receiving aphysical broadcast channel (PBCH) from the eNB. During the initial cellsearch, the UE may monitor a DL channel state by receiving a downlinkreference signal (DL RS).

After the initial cell search, the UE may acquire detailed systeminformation by receiving a physical downlink control channel (PDCCH) andreceiving a physical downlink shared channel (PDSCH) based oninformation included in the PDCCH (S202).

If the UE initially accesses the eNB or has no radio resources forsignal transmission to the eNB, the UE may perform a random accessprocedure with the eNB (S203 to S206). In the random access procedure,the UE may transmit a predetermined sequence as a preamble on a physicalrandom access channel (PRACH) (S203 and S205) and may receive a responsemessage to the preamble on a PDCCH and a PDSCH associated with the PDCCH(S204 and S206). In the case of a contention-based RACH, the UE mayadditionally perform a contention resolution procedure.

After the above procedure, the UE may receive a PDCCH and/or a PDSCHfrom the eNB (S207) and transmit a physical uplink shared channel(PUSCH) and/or a physical uplink control channel (PUCCH) to the eNB(S208), which is a general DL and UL signal transmission procedure.Particularly, the UE receives downlink control information (DCI) on aPDCCH. Herein, the DCI includes control information such as resourceallocation information for the UE. Different DCI formats are definedaccording to different usages of DCI.

Control information that the UE transmits to the eNB on the UL orreceives from the eNB on the DL includes a DL/UL acknowledgment/negativeacknowledgment (ACK/NACK) signal, a channel quality indicator (CQI), aprecoding matrix index (PMI), a rank indicator (RI), etc. In the 3GPPLTE system, the UE may transmit control information such as a CQI, aPMI, an RI, etc. on a PUSCH and/or a PUCCH.

The use of an ultra-high frequency band, that is, a millimeter frequencyband at or above 6 GHz is under consideration in the NR system totransmit data in a wide frequency band, while maintaining a hightransmission rate for multiple users. The 3GPP calls this system NR. Inthe present disclosure, the system will also be referred to as an NRsystem.

FIG. 3 illustrates a structure of a radio frame used in NR.

In NR, UL and DL transmissions are configured in frames. The radio framehas a length of 10 ms and is defined as two 5-ms half-frames (HF). Thehalf-frame is defined as five 1 ms subframes (SF). A subframe is dividedinto one or more slots, and the number of slots in a subframe depends onsubcarrier spacing (SCS). Each slot includes 12 or 14 OFDM(A) symbolsaccording to a cyclic prefix (CP). When a normal CP is used, each slotincludes 14 symbols. When an extended CP is used, each slot includes 12symbols. Here, the symbols may include OFDM symbols (or CP-OFDM symbols)and SC-FDMA symbols (or DFT-s-OFDM symbols).

[Table 1] illustrates that the number of symbols per slot, the number ofslots per frame, and the number of slots per subframe vary according tothe SCS when the normal CP is used.

TABLE 1 SCS (15*2{circumflex over ( )}u) N^(slot) _(symb) N^(frame,u)_(slot) N^(subframe,u) _(slot)  15 KHz (u = 0) 14 10 1  30 KHz (u = 1)14 20 2  60 KHz (u = 2) 14 40 4 120 KHz (u = 3) 14 80 8 240 KHz (u = 4)14 160 16 *Nslotsymb: Number of symbols in a slot *Nframe,uslot: Numberof slots in a frame *Nsubframe,uslot: Number of slots in a subframe

[Table 2] illustrates that the number of symbols per slot, the number ofslots per frame, and the number of slots per subframe vary according tothe SCS when the extended CP is used.

TABLE 2 SCS (15*2{circumflex over ( )}u) N^(slot) _(symb) N^(frame,u)_(slot) N^(subframe,u) _(slot) 60 KHz (u = 2) 12 40 4

In the NR system, the OFDM(A) numerology (e.g., SCS, CP length, etc.)may be configured differently among a plurality of cells merged for oneUE. Thus, the (absolute time) duration of a time resource (e.g., SF,slot or TTI) (referred to as a time unit (TU) for simplicity) composedof the same number of symbols may be set differently among the mergedcells. FIG. 4 illustrates a slot structure of an NR frame. A slotincludes a plurality of symbols in the time domain. For example, in thecase of the normal CP, one slot includes seven symbols. On the otherhand, in the case of the extended CP, one slot includes six symbols. Acarrier includes a plurality of subcarriers in the frequency domain. Aresource block (RB) is defined as a plurality of consecutive subcarriers(e.g., 12 consecutive subcarriers) in the frequency domain. A bandwidthpart (BWP) is defined as a plurality of consecutive (P)RBs in thefrequency domain and may correspond to one numerology (e.g., SCS, CPlength, etc.). A carrier may include up to N (e.g., 4) BWPs. Datacommunication is performed through an activated BWP, and only one BWPmay be activated for one UE. In the resource grid, each element isreferred to as a resource element (RE), and one complex symbol may bemapped thereto.

FIG. 5 illustrates a structure of a self-contained slot. In the NRsystem, a frame has a self-contained structure in which a DL controlchannel, DL or UL data, a UL control channel, and the like may all becontained in one slot. For example, the first N symbols (hereinafter, DLcontrol region) in the slot may be used to transmit a DL controlchannel, and the last M symbols (hereinafter, UL control region) in theslot may be used to transmit a UL control channel N and M are integersgreater than or equal to 0. A resource region (hereinafter, a dataregion) that is between the DL control region and the UL control regionmay be used for DL data transmission or UL data transmission. Forexample, the following configuration may be considered. Respectivesections are listed in a temporal order.

1. DL only configuration

2. UL only configuration

3. Mixed UL-DL configuration

-   -   DL region+Guard period (GP)+UL control region    -   DL control region+GP+UL region    -   DL region: (i) DL data region, (ii) DL control region+DL data        region    -   UL region: (i) UL data region, (ii) UL data region+UL control        region

The PDCCH may be transmitted in the DL control region, and the PDSCH maybe transmitted in the DL data region. The PUCCH may be transmitted inthe UL control region, and the PUSCH may be transmitted in the UL dataregion. Downlink control information (DCI), for example, DL datascheduling information, UL data scheduling information, and the like,may be transmitted on the PDCCH. Uplink control information (UCI), forexample, ACK/NACK information about DL data, channel state information(CSI), and a scheduling request (SR), may be transmitted on the PUCCH.The GP provides a time gap in the process of the UE switching from thetransmission mode to the reception mode or from the reception mode tothe transmission mode. Some symbols at the time of switching from DL toUL within a subframe may be configured as the GP.

FIG. 6 illustrates an exemplary wireless communication system supportingan unlicensed band, which is applicable to the present disclosure.

In the following description, a cell operating in a licensed band(hereinafter, referred to as an L-band) is defined as an L-cell, and thecarrier of an L-cell is defined as a (DL/UL) LCC. Further, a celloperating in an unlicensed band (hereinafter, referred to as a U-band)is defined as a U-cell and the carrier of a U-cell is defined as a(DL/UL) UCC. The carrier/carrier-frequency of a cell may refer to theoperating frequency (e.g., center frequency) of the cell. A cell/carrier(e.g., component carrier (CC)) is genetically referred to as a cell.

When a UE and a BS transmit and receive signals in a carrier-aggregatedLCC and UCC as illustrated in FIG. 6(a), the LCC may be configured as aprimary CC (PCC) and the UCC may be configured as a secondary CC (SCC).As illustrated in FIG. 6(b), the UE and the BS may transmit and receivesignals in one UCC or a plurality of carrier-aggregated UCCs. That is,the UE and the BS may transmit and receive signals only in UCC(s)without an LCC.

(Unless otherwise specified), a signal transmission/reception operationin an unlicensed band described in the present disclosure may beperformed based on all the above-described deployment scenarios.

The NR frame structure of FIG. 5 may be used for an operation in anunlicensed band. The configuration of OFDM symbols occupied for UL/DLsignal transmission in the frame structure for the unlicensed band maybe configured by the BS. The term OFDM symbol may be replaced withSC-FDM(A) symbol.

To transmit a DL signal in an unlicensed band, the BS may indicate theconfiguration of OFDM symbols used in subframe #n to the UE bysignaling. The term subframe may be replaced with slot or time unit(TU).

Specifically, in an LTE system supporting an unlicensed band, the UE mayassume (or identify) the configuration of OFDM symbols occupied insubframe #n by a specific field (e.g., a Subframe configuration for LAAfield or the like) in DCI received in subframe #n−1 or subframe #n fromthe BS.

Table 3 describes a method of indicating the configuration of OFDMsymbols used for transmission of a DL physical channel and/or physicalsignal in a current and/or next subframe by the Subframe configurationfor LAA field in the LTE system.

TABLE 3 Value of Configuration ‘Subframe configuration of occupied OFDMfor LAA’ field symbols (current subframe, in current subframe nextsubframe) 0000 (—, 14) 0001 (—, 12) 0010 (—, 11) 0011 (—, 10) 0100 (—,9) 0101 (—, 6) 0110 (—, 3) 0111 (14, *) 1000 (12, —) 1001 (11, —) 1010(10, —) 1011 (9, —) 1100 (6, —) 1101 (3, —) 1110 reserved 1111 reservedNOTE:— (—, Y) means UE may assume the first Y symbols are occupied innext subframe and other symbols in the next subframe are notoccupied.—(X, —) means UE may assume the first X symbols are occupied incurrent subframe and other symbols in the current subframe are notoccupied.—(X, *) means UE may assume the first X symbols are occupied incurrent subframe, and at least the first OFDM symbol of the nextsubframe is not occupied.

For UL signal transmission in an unlicensed band, the BS may indicate aUL transmission period to the UE by signaling.

Specifically in the LTE system supporting an unlicensed band, the UE mayobtain ‘UL duration’ and ‘UL offset’ information for subframe #n from a‘UL duration and offset’ field in detected DCI.

Table 4 illustrates a method of indicating the configuration of a ULoffset and a UL duration by the UL duration and offset field in the LTEsystem.

TABLE 4 Value of ‘UL duration and UL offset, l UL duration, d offset’field (in subframes) (in subframes) 00000 Not configured Not configured00001 1 1 00010 1 2 00011 1 3 00100 1 4 00101 1 5 00110 1 6 00111 2 101000 2 2 01001 2 3 01010 2 4 01011 2 5 01100 2 6 01101 3 1 01110 3 201111 3 3 10000 3 4 10001 3 5 10010 3 6 10011 4 1 10100 4 2 10101 4 310110 4 4 10111 4 5 11000 4 6 11001 6 1 11010 6 2 11011 6 3 11100 6 411101 6 5 11110 6 6 11111 reserved reserved

For example, if the UL duration and offset field configures (orindicates) UL offset 1 and UL duration d for subframe #n, the UE doesnot need to receive a DL physical channel and/or physical signal insubframe #(n+l+i) (where i=0, 1, . . . , d−1).

The BS may perform one of the following unlicensed band accessprocedures (e.g., channel access procedures (CAPs)) to transmit a DLsignal in the unlicensed band.

(1) First DL CAP Method

FIG. 7 is a flowchart illustrating a DL CAP for DL signal transmissionin an unlicensed band, performed by a BS.

For DL signal transmission (e.g., transmission of a DL signal such as aPDSCH/PDCCH/enhanced PDCCH (EPDCCH)), the BS may initiate a CAP (S710).The BS may randomly select a backoff counter N within a contentionwindow (CW) according to step 1. N is set to an initial value Ninit(S720). Ninit is a random value selected from the values between 0 andCWp. Subsequently, when the backoff counter value N is 0 according tostep 4 (S730; Y), the BS terminates the CAP (S732). The BS may thenperform a Tx burst transmission including transmission of aPDSCH/PDCCH/EPDCCH (S734). On the contrary, when the backoff countervalue N is not 0 (S730; N), the BS decrements the backoff counter valueby 1 according to step 2 (S740). Subsequently, the BS checks whether thechannel of U-cell(s) is idle (S750). If the channel is idle (S750; Y),the BS determines whether the backoff counter value is 0 (S730). On thecontrary, when the channel is not idle, that is, the channel is busy(S750; N), the BS determines whether the channel is idle during a longerdefer duration Td (25 usec or longer) than a slot duration (e.g., 9usec) according to step 5 (S760). If the channel is idle during thedefer duration (S770; Y), the BS may resume the CAP. The defer durationmay include a 16-usec duration and the immediately following mpconsecutive slot durations (e.g., each being 9 usec). On the contrary,if the channel is busy during the defer duration (S770; N), the BSre-checks whether the channel of the U-cell(s) is idle during a newdefer duration by performing step S760 again.

Table 5 illustrates that mp, a minimum CW, a maximum CW, a maximumchannel occupancy time (MCOT), and an allowed CW size applied to a CAPvary according to channel access priority classes.

TABLE 5 Channel Access Priority Class CW CW Allowed DW (p) mp min, pmax, p T ultcot, p p sizes 1 1 3 7 2 ms {3, 7} 2 1 7 15 3 ms {7, 15} 3 315 63 8 or 10 ms {15, 31, 63} 4 7 15 1023 8 or 10 ms {15, 31, 63, 127,255, 511, 1023}

A CW size applied to the first DL CAP may be determined in variousmethods. For example, the CW size may be adjusted based on theprobability of HARQ-ACK values corresponding to PDSCH transmission(s)within a predetermined time period (e.g., a reference TU) beingdetermined as NACK. In the case where the BS performs a DL transmissionincluding a PDSCH that is associated with a channel access priorityclass p on a carrier, if the probability z of HARQ-ACK valuescorresponding to PDSCH transmission(s) in reference subframe k (orreference slot k) being determined as NACK is at least 80%, the BSincreases a CW value set for each priority class to the next higherallowed value. Alternatively, the BS maintains the CW value set for eachpriority class to be an initial value. A reference subframe (orreference slot) may be defined as the starting subframe (or slot) of themost recent transmission on the carrier made by the BS, for which atleast some HARQ-ACK feedback is expected to be available.

(2) Second DL CAP Method

The BS may perform a DL signal transmission (e.g., a signal transmissionincluding a discovery signal transmission, without a PDSCH) in anunlicensed band according to the second DL CAP method described below.

When the signal transmission duration of the BS is equal to or less than1 ms, the BS may transmit a DL signal (e.g., a signal including adiscovery signal without a PDSCH) in the unlicensed band immediatelyafter sensing the channel to be idle for at least a sensing durationTdrs=25 us. Tdrs includes a duration Tf (=16 us) following one sensingslot duration Tsl (=9 us).

(3) Third DL CAP Method

The BS may perform the following CAPs for DL signal transmission onmultiple carriers in an unlicensed band.

1) Type A: The BS performs a CAP for multiple carriers based on acounter N defined for each carrier (a counter N considered in a CAP) andperforms a DL signal transmission based on the CAP.

-   -   Type A1: The counter N for each carrier is determined        independently, and a DL signal is transmitted on each carrier        based on the counter N for the carrier.    -   Type A2: The counter N of a carrier with a largest CW size is        set for each carrier, and a DL signal is transmitted on each        carrier based on the counter N for the carrier.

2) Type B: The BS performs a CAP based on a counter N only for aspecific one of a plurality of carriers and performs a DL signaltransmission by checking whether the channels of the other carriers areidle before a signal transmission on the specific carrier.

-   -   Type B1: A single CW size is defined for a plurality of        carriers, and the BS uses the single CW size in a CAP based on        the counter N for a specific carrier.    -   Type B2: A CW size is defined for each carrier, and the largest        of the CW sizes is used in determining Ninit for a specific        carrier.

Further, the UE performs a contention-based CAP for a UL signaltransmission in an unlicensed band. The UE performs a Type 1 or Type 2CAP for the UL signal transmission in the unlicensed band. In general,the UE may perform a CAP (e.g., Type 1 or Type 2) configured for a ULsignal transmission by the BS.

(1) Type 1 UL CAP Method

FIG. 8 is a flowchart illustrating UE's Type 1 CAP operation for ULsignal transmission.

To transmit a signal in the U-band, the UE may initiate a CAP (S810).The UE may randomly select a backoff counter N within a contentionwindow (CW) according to step 1. In this case, N is set to an initialvalue Ninit (S820). Ninit may have a random value between 0 and CWp. Ifit is determined according to step 4 that the backoff counter value (N)is 0 (YES in S830), the UE terminates the CAP (S832). Then, the UE mayperform Tx burst transmission (S834). If the backoff counter value isnon-zero (NO in S830), the UE decreases the backoff counter value by 1according to step 2 (S840). The UE checks whether the channel ofU-cell(s) is idle (S850). If the channel is idle (YES in S850), the UEchecks whether the backoff counter value is 0 (S830). On the contrary,if the channel is not idle in S850, that is, if the channel is busy (NOin S850), the UE checks whether the corresponding channel is idle for adefer duration Td (longer than or equal to 25 usec), which is longerthan a slot duration (e.g., 9 usec), according to step 5 (S860). If thechannel is idle for the defer duration (YES in S870), the UE may resumethe CAP. Here, the defer duration may include a duration of 16 usec andmp consecutive slot durations (e.g., 9 usec), which immediately followsthe duration of 16 usec. If the channel is busy for the defer duration(NO in S870), the UE performs step S1260 again to check whether thechannel is idle for a new defer duration.

Table 6 shows that the values of mp, a minimum CW, a maximum CW, anMCOT, and allowed CW sizes, which are applied to the CAP, vary dependingon channel access priority classes.

TABLE 6 Channel Access Priority Class allowed CW_(p) (p) C CT_(ulmcot,p) sizes 1 3 7 2 ms {3, 7} 2 7 15 4 ms {7, 15} 3 15 1023 6 msor 10 ms {15, 31, 63, 127, 255, 511, 1023} 4 15 1023 6 ms or 10 ms {15,31, 63, 127, 255, 511, 1023} NOTE 1: For p = 3, 4, T_(ulmcot,p) = 10 msif the higher layer parameter ‘absenceOfAnyOtherTechnology-r14’indicates TRUE, otherwise, T_(ulmcot,p) = 6 ms. NOTE 2: WhenT_(ulmcot,p) = 6 ms it may be increased to 8 ms by inserting one or moregaps. The minimum duration of a gap shall be 100 μs. The maximumduration before including any such gap shall be 6 ms.

The size of a CW applied to the Type 1 UL CAP may be determined invarious ways. For example, the CW size may be adjusted depending onwhether the value of a new data indicator (NDI) for at least one HARQprocess associated with HARQ_ID_ref, which is the HARQ process ID of aUL-SCH in a predetermined time period (e.g., a reference TU), istoggled. When the UE performs signal transmission using the Type 1 CAPassociated with the channel access priority class p on a carrier, if thevalue of the NDI for the at least one HARQ process associated withHARQ_ID_ref is toggled, the UE may set CWp to CWmin, p for everypriority class p∈{1,2,3,4}. Otherwise, the UE may increase CWp for everypriority class p∈{1,2,3,4} to a next higher allowed value.

A reference subframe (or reference slot) nref may be determined asfollows.

When the UE receives a UL grant in a subframe (or slot) ng and performstransmission including a UL-SCH, which has no gaps and starts from asubframe (or slot) n0, in subframes (or slots) n₀, n₁, . . . , n_(w)(here, the subframe (or slot) nw is the most recent subframe (or slot)before a subframe ng-3 in which the UE has transmitted the UL-SCH basedon the Type 1 CAP), the reference subframe (or slot) nref may be thesubframe n0.

(2) Type 2 UL CAP Method

When the UE uses the Type 2 CAP to transmit a UL signal (including thePUSCH) in a U-band, the UE may transmit the UL signal (including thePUSCH) in the U-band immediately after sensing that the channel is idleat least for a sensing period Tshort_ul of 25 us. Tshort_ul includes aduration Tf of 16 us immediately followed by one slot duration Tsl of 9us. Tf includes an idle slot duration Tsl at the start thereof.

In the NR system, a massive multiple input multiple output (MIMO)environment in which the number of transmission/reception (Tx/Rx)antennas is significantly increased may be under consideration. That is,as the massive MIMO environment is considered, the number of Tx/Rxantennas may be increased to a few tens or hundreds. The NR systemsupports communication in an above 6 GHz band, that is, a millimeterfrequency band. However, the millimeter frequency band is characterizedby the frequency property that a signal is very rapidly attenuatedaccording to a distance due to the use of too high a frequency band.Therefore, in an NR system operating at or above 6 GHz, beamforming (BF)is considered, in which a signal is transmitted with concentrated energyin a specific direction, not omni-directionally, to compensate for rapidpropagation attenuation. Accordingly, there is a need for hybrid BF withanalog BF and digital BF in combination according to a position to whicha BF weight vector/precoding vector is applied, for the purpose ofincreased performance, flexible resource allocation, and easiness offrequency-wise beam control in the massive MIMO environment.

FIG. 9 is a block diagram illustrating an exemplary transmitter andreceiver for hybrid BF.

To form a narrow beam in the millimeter frequency band, a BF method ismainly considered, in which a BS or a UE transmits the same signalthrough multiple antennas by applying appropriate phase differences tothe antennas and thus increasing energy only in a specific direction.Such BF methods include digital BF for generating a phase difference fordigital baseband signals, analog BF for generating phase differences byusing time delays (i.e., cyclic shifts) for modulated analog signals,and hybrid BF with digital BF and analog beamforming in combination. Useof a radio frequency (RF) unit (or transceiver unit (TXRU)) for antennaelement to control transmission power and phase control on antennaelement basis enables independent BF for each frequency resource.However, installing TXRUs in all of about 100 antenna elements is lessfeasible in terms of cost. That is, a large number of antennas arerequired to compensate for rapid propagation attenuation in themillimeter frequency, and digital BF needs as many RF components (e.g.,digital-to-analog converters (DACs), mixers, power amplifiers, andlinear amplifiers) as the number of antennas. As a consequence,implementation of digital BF in the millimeter frequency band increasesthe prices of communication devices. Therefore, analog BF or hybrid BFis considered, when a large number of antennas are needed as is the casewith the millimeter frequency band. In analog BF, a plurality of antennaelements are mapped to a single TXRU and a beam direction is controlledby an analog phase shifter. Because only one beam direction is generatedacross a total band in analog BF, frequency-selective BF may not beachieved with analog BF. Hybrid BF is an intermediate form of digital BFand analog BF, using B RF units fewer than Q antenna elements. In hybridBF, the number of beam directions available for simultaneoustransmission is limited to B or less, which depends on how B RF unitsand Q antenna elements are connected.

Downlink Beam Management (DL BM)

BM is a series of processes for acquiring and maintaining a set of BS(or transmission and reception point (TRP)) beams and/or UE beamsavailable for DL and UL transmissions/receptions. BM may include thefollowing processes and terminology.

-   -   Beam measurement: the BS or the UE measures the characteristics        of a received beamformed signal.    -   Beam determination: the BS or the UE selects its Tx beam/Rx        beam.    -   Beam sweeping: a spatial domain is covered by using Tx beams        and/or Rx beams in a predetermined manner during a predetermined        time interval.    -   Beam report: the UE reports information about a beamformed        signal based on a beam measurement.

The BM procedure may be divided into (1) a DL BM procedure using an SSBor CSI-RS and (2) a UL BM procedure using an SRS. Further, each BMprocedure may include Tx beam sweeping for determining a Tx beam, and Rxbeam sweeping for determining an Rx beam.

The DL BM procedure may include (1) transmission of beamformed DL RSs(e.g., CSI-RS or SSB) from the BS and (2) beam reporting from the UE.

A beam report may include preferred DL RS ID(s) and reference signalreceived power(s) (RSRP(s)) corresponding to the preferred DL RS ID(s).A DL RS ID may be an SSB resource indicator (SSBRI) or a CSI-RS resourceindicator (CRI).

FIG. 10 is a diagram illustrating exemplary BF using an SSB and aCSI-RS.

Referring to FIG. 10, an SSB beam and a CSI-RS beam may be used for beammeasurement. A measurement metric is the RSRP of each resource/block.The SSB may be used for coarse beam measurement, whereas the CSI-RS maybe used for fine beam measurement. The SSB may be used for both Tx beamsweeping and Rx beam sweeping. SSB-based Rx beam sweeping may beperformed by attempting to receive the SSB for the same SSBRI, whilechanging an Rx beam across multiple SSB bursts at a UE. One SS burstincludes one or more SSBs, and one SS burst set includes one or more SSBbursts.

1. DL BM Using SSB

FIG. 11 is a diagram illustrating a signal flow for an exemplary DL BMprocess using an SSB.

An SSB-based beam report is configured during CSI/beam configuration inRRC_CONNECTED mode.

-   -   A UE receives a CSI-ResourceConfig information element (IE)        including CSI-SSB-ResourceSetList for SSB resources used for BM        from a BS (S1110). The RRC parameter, CSI-SSB-ResourceSetList is        a list of SSB resources used for BM and reporting in one        resource set. The SSB resource set may be configured as {SSBx1,        SSBx2, SSBx3, SSBx4}. SSB indexes may range from 0 to 63.    -   The UE receives signals in the SSB resources from the BS based        on CSI-SSB-ResourceSetList (S1120).    -   When CSI-RS reportConfig related to an SSBRI and RSRP reporting        has been configured, the UE reports a best SSBRI and an RSRP        corresponding to the best SSBRI to the BS (S1130). For example,        when reportQuantity in the CSI-RS reportConfig IE is set to        ‘ssb-Index-RSRP’, the UE reports the best SSBRI and the RSRP        corresponding to the best SSBRI to the BS.

When CSI-RS resources are configured in OFDM symbol(s) carrying an SSBand ‘QCL-TypeD’ is applicable to the CSI-RS resources and the SSB, theUE may assume that a CSI-RS and the SSB are quasi-co-located (QCLed)from the perspective of ‘QCL-TypeD’. QCL-TypeD may mean that antennaports are QCLed from the perspective of spatial Rx parameters. When theUE receives signals from a plurality of DL antenna ports placed in theQCL-TypeD relationship, the UE may apply the same Rx beam to thesignals.

2. DL BM Using CSI-RS

The CSI-RS serves the following purposes: i) when Repetition isconfigured and TRS_info is not configured for a specific CSI-RS resourceset, the CSI-RS is used for BM; ii) when Repetition is not configuredand TRS_info is configured for the specific CSI-RS resource set, theCSI-RS is used for a tracking reference signal (TRS); and iii) wheneither of Repetition or TRS_info is configured for the specific CSI-RSresource set, the CSI-RS is used for CSI acquisition.

When (the RRC parameter) Repetition is set to ‘ON’, this is related tothe Rx beam sweeping process of the UE. In the case where Repetition isset to ‘ON’, when the UE is configured with NZP-CSI-RS-ResourceSet, theUE may assume that signals in at least one CSI-RS resource withinNZP-CSI-RS-ResourceSet are transmitted through the same DL spatialdomain filter. That is, the at least one CSI-RS resource withinNZP-CSI-RS-ResourceSet is transmitted on the same Tx beam. The signalsin the at least one CSI-RS resource within NZP-CSI-RS-ResourceSet may betransmitted in different OFDM symbols.

On the contrary, when Repetition is set to ‘OFF’, this is related to theTx beam sweeping process of the BS. In the case where Repetition is setto ‘OFF’, the UE does not assume that signals in at least one CSI-RSresource within NZP-CSI-RS-ResourceSet are transmitted through the sameDL spatial domain filter. That is, the signals in the at least oneCSI-RS resource within NZP-CSI-RS-ResourceSet are transmitted ondifferent Tx beams. FIG. 12 illustrates another exemplary DL BM processusing a CSI-RS.

FIG. 12(a) illustrates an Rx beam refinement process of a UE, and FIG.12(b) illustrates a Tx beam sweeping process of a BS. Further, FIG.12(a) is for a case in which Repetition is set to ‘ON’, and FIG. 12(b)is for a case in which Repetition is set to ‘OFF’.

With reference to FIGS. 12(a) and 13(a), an Rx beam determinationprocess of a UE will be described below.

FIG. 13(a) is a diagram illustrating a signal flow for an exemplary Rxbeam determination process of a UE.

-   -   The UE receives an NZP CSI-RS resource set IE including an RRC        parameter ‘Repetition’ from a BS by RRC signaling (S1210). The        RRC parameter ‘Repetition’ is set to ‘ON’ herein.    -   The UE repeatedly receives signals in resource(s) of a CSI-RS        resource set for which the RRC parameter ‘Repetition’ is set to        ‘ON’ on the same Tx beam (or DL spatial domain Tx filter) of the        BS in different OFDM symbols (S1220).    -   The UE determines its Rx beam (S1230).    -   The UE skips CSI reporting (S1240). That is, the UE may skip CSI        reporting, when the RRC parameter ‘Repetition’ is set to ‘ON’.

With reference to FIGS. 12(b) and 13(b), a Tx beam determination processof a BS will be described below.

FIG. 13(b) is a diagram illustrating an exemplary Tx beam determinationprocess of a BS.

-   -   A UE receives an NZP CSI-RS resource set IE including an RRC        parameter ‘Repetition’ from the BS by RRC signaling (S1350).        When the RRC parameter ‘Repetition’ is set to ‘OFF’, this is        related to a Tx beam sweeping process of the BS.    -   The UE receives signals in resource(s) of a CSI-RS resource set        for which the RRC parameter ‘Repetition’ is set to ‘OFF’ on        different Tx beams (or DL spatial domain Tx filters) of the BS        (S1360).    -   The UE selects (or determines) a best beam (S1370).    -   The UE reports the ID (e.g., CRI) of the selected beam and        related quality information (e.g., an RSRP) to the BS (S1380).        That is, the UE reports a CRI and an RSRP corresponding to the        CRI, when a CSI-RS is transmitted for BM.

FIG. 14 is a diagram illustrating exemplary resource allocation in thetime and frequency domains, which is related to the operation of FIG.12.

When Repetition is set to ‘ON’ for a CSI-RS resource set, a plurality ofCSI-RS resources may be repeatedly used on the same Tx beam, whereaswhen Repetition is set to ‘OFF’ for the CSI-RS resource set, differentCSI-RS resources may be repeatedly transmitted on different Tx beams.

3. DL BM-Related Beam Indication

The UE may receive at least a list of up to M candidate transmissionconfiguration indication (TCI) states for QCL indication by RRCsignaling. M depends on a UE capability and may be 64.

Each TCI state may be configured with one RS set. Table 7 describes anexample of a TCI-State IE. The TC-State IE is related to a QCL typecorresponding to one or two DL RSs.

TABLE 7  -- ASN1START  -- TAG-TCI-STATE-START  TCI-State ::=  SEQUENCE {  tci-StateId    TCI-StateId,   qc1-Type1   QCL-Info,   qc1-Type2   QCL-Info     OPTIONAL, -- Need R   . . .  }  QCL-Info ::= SEQUENCE {   cell  ServCellIndex OPTIONAL, -- Need R   bwp-Id   BWP- Id     OPTIONAL, --Cond CSI-RS-Indicated   referenceSignal    CHOICE {    csi-rs   NZP-CSI-RS-ResourceId,    ssb    SSB-Index   },   qc1-Type  ENUMERATED {typeA, typeB, typeC, typeD},   . . .  }  --TAG-TCI-STATE-STOP  -- ASN1STOP

In Table 7, ‘bwp-Id’ identifies a DL BWP in which an RS is located,‘cell’ indicates a carrier in which the RS is located, and‘referencesignal’ indicates reference antenna port(s) serving as a QCLsource for target antenna port(s) or an RS including the referenceantenna port(s). The target antenna port(s) may be for a CSI-RS, PDCCHDMRS, or PDSCH DMRS.

4. Quasi-Co Location (QCL)

The UE may receive a list of up to M TCI-State configurations to decodea PDSCH according to a detected PDCCH carrying DCI intended for a givencell. M depends on a UE capability.

As described in Table 7, each TCI-State includes a parameter forestablishing the QCL relationship between one or more DL RSs and a PDSCHDM-RS port. The QCL relationship is established with an RRC parameterqcl-Type1 for a first DL RS and an RRC parameter qcl-Type2 for a secondDL RS (if configured).

The QCL type of each DL RS is given by a parameter ‘qcl-Type’ includedin QCL-Info and may have one of the following values.

-   -   ‘QCL-TypeA’: {Doppler shift, Doppler spread, average delay,        delay spread}    -   ‘QCL-TypeB’: {Doppler shift, Doppler spread}    -   ‘QCL-TypeC’: {Doppler shift, average delay}    -   ‘QCL-TypeD’: {Spatial Rx parameter}

For example, if a target antenna port is for a specific NZP CSI-RS, theNZP CSI-RS antenna port may be indicated/configured as QCLed with aspecific TRS from the perspective of QCL-Type A and with a specific SSBfrom the perspective of QCL-Type D. Upon receipt of thisindication/configuration, the UE may receive the NZP CSI-RS using aDoppler value and a delay value which are measured in a QCL-TypeA TRS,and apply an Rx beam used to receive a QCL-Type D SSB for reception ofthe NZP CSI-RS.

CSI-Related Operations

In the NR system, a CSI-RS is used for time/frequency tracking, CSIcomputation, reference signal received power (RSRP) calculation, andmobility. CSI computation is related to CSI acquisition, and RSRPcomputation is related to beam management (BM).

FIG. 15 is a diagram illustrating a signal flow for a CSI-relatedprocess.

-   -   For one of the above-described uses of the CSI-RS, a UE receives        CSI-related configuration information from a BS by RRC signaling        (S1501).

The CSI-related configuration information may include at least one ofchannel state information interference measurement (CSI-IM)resource-related information, CSI measurement configuration-relatedinformation, CSI resource configuration-related information, CSI-RSresource-related information, or CSI report configuration-relatedinformation.

i) The CSI-IM resource-related information may include CSI-IM resourceinformation, CSI-IM resource set information, and so on. A CSI-IMresource set is identified by a CSI-IM resource set ID, and one CSI-IMresource set includes at least one CSI-IM resource. Each CSI-IM resourceis identified by a CSI-IM resource ID.

ii) The CSI resource configuration-related information may berepresented by a CSI-ResourceConfig information element (IE). The CSIresource configuration-related information defines a group including atleast one of a non-zero power (NZP) CSI-RS resource set, a CSI-IMresource set, or a CSI-SSB resource set. That is, the CSI resourceconfiguration-related information may include a CSI-RS resource setlist, and the CSI-RS resource set list may include at least one of anNZP CSI-RS resource set list, a CSI-IM resource set list, or a CSI-SSBresource set list. The CSI-RS resource set is identified by a CSI-RSresource set ID, and one CSI-RS resource set includes at least oneCSI-RS resource. Each CSI-RS resource is identified by a CSI-RS resourceID.

An RRC parameter indicating the use of a CSI-RS (e.g., a BM-relatedparameter ‘repetition’ and a tracking-related parameter ‘trs-Info’) maybe configured for each NZP CSI-RS resource set.

iii) The CSI report configuration-related information includes aparameter indicating a time-domain behavior, reportConfigType and aparameter indicating a CSI-related quantity to be reported,reportQuantity. The time-domain behavior may be periodic, aperiodic, orsemi-persistent.

-   -   The UE measures CSI based on the CSI-related configuration        information (S1505). The CSI measurement may include (1) CSI-RS        reception of the UE (S1503) and (2) CSI computation in the        received CSI-RS (S1507). Mapping of the CSI-RS to REs of CSI-RS        resources in the time and frequency domains is configured by an        RRC parameter, CSI-RS-ResourceMapping.    -   The UE reports the measured CSI to the BS (S1509).

1. CSI Measurement

The NR system supports more flexible and more dynamic CSI measurementand reporting. The CSI measurement may include reception of a CSI-RS andmeasurement of the received CSI-RS to acquire CSI.

As the time-domain behavior of CSI measurement and reporting, channelmeasurement (CM) and interference measurement (IM) are supported.

A CSI-IM-based IM resource (IMR) is designed in NR, similarly to aCSI-IM in LTE and configured independently of a zero power (ZP) CSI-RSresource for PDSCH rate matching.

The BS transmits an NZP CSI-RS to the UE on each port of a configuredNZP CSI-RS-based IMR.

When there is no PMI and RI feedback for a channel, multiple resourcesare configured in a set, and the BS or network indicates a subset of NZPCSI-RS resources for channel measurement and/or interference measurementby DCI.

A resource setting and a resource setting configuration will bedescribed in greater detail.

1.1. Resource Setting

Each CSI resource setting ‘CSI-ResourceConfig’ includes a configurationof S≥1 CSI resource sets (given by an RRC parametercsi-RS-ResourceSetList). S represents the number of configured CSI-RSresource sets. The configuration of S≥1 CSI resource sets includes eachCSI resource set including (NZP CSI-RS or CSI-IM) CSI-RS resources, andSSB resources used for RSRP computation.

Each CSI resource setting is located in a DL BWP identified by an RRCparameter bwp-id. All CSI resource settings linked to a CSI reportingsetting have the same DL BWP.

The time-domain behavior of a CSI-RS resource within theCSI-ResourceConfig 1E is indicated by an RRC parameter resourceType inthe CSI resource setting, and may be set to aperiodic, periodic, orsemi-persistent.

One or more CSI resource settings for channel measurement andinterference measurement are configured by RRC signaling. A channelmeasurement resource (CMR) may be an NZP CSI-RS for CSI acquisition, andan IMR may be an NZP CSI-RS for CSI-IM and IM. The CSI-IM (or ZP CSI-RSfor IM) is mainly used for inter-cell measurement. The NZP CSI-RS for IMis used mainly for measurement of intra-cell interference from multipleusers.

The UE may assume that CSI-RS resource(s) for channel measurement andCSI-IM/NZP CSI-RS resource(s) for interference measurement configuredfor one CSI report are resource-wise quasi co-located (QCLed) withrespect to ‘QCL-TypeD’.

1.2. Resource Setting Configuration

A resource setting may mean a resource set list, and one reportingsetting may be linked to up to three resource settings.

-   -   When one resource setting is configured, the resource setting        (given by an RRC parameter resourcesForChannelMeasurement) is        for channel measurement for RSRP computation.    -   When two resource settings are configured, the first resource        setting (given by the RRC parameter        resourcesForChannelMeasurement) is for channel measurement and        the second resource setting (given by        csi-IM-ResourcesForInterference or        nzp-CSI-RS-ResourcesForInterference) is for interference        measurement on the CSI-IM or on the NZP CSI-RS.    -   When three resource settings are configured, the first resource        setting (given by resourcesForChannelMeasurement) is for channel        measurement, the second resource setting (given by        csi-IM-ResourcesForInterference) is for CSI-IM-based        interference measurement, and the third resource setting (given        by nzp-CSI-RS-ResourcesForInterference) is for NZP CSI-RS-based        interference measurement.    -   When one resource setting (given by        resourcesForChannelMeasurement) is configured, the resource        setting is for channel measurement for RSRP computation.    -   When two resource settings are configured, the first resource        setting (given by resourcesForChannelMeasurement) is for channel        measurement and the second resource setting (given by the RRC        parameter csi-IM-ResourcesForInterference) is used for        interference measurement performed on the CSI-IM.

1.3. CSI Computation

If interference measurement is performed on the CSI-IM, each CSI-RSresource for channel measurement is resource-wise associated with aCSI-IM resource by the ordering of the CSI-RS resources and CSI-IMresources in a corresponding resource set. The number of CSI-RSresources for channel measurement equals to the number of CSI-IMresources.

For CSI measurement, the UE assumes the following.

-   -   Each NZP CSI-RS port configured for interference measurement        corresponds to an interference transmission layer.    -   All interference transmission layers on NZP CSI-RS ports for        interference measurement take into account energy per resource        element (EPRE) ratios.    -   The UE assumes another interference signal on RE(s) of NZP        CSI-RS resources for channel measurement, NZP CSI-RS resources        for interference measurement, or CSI-IM resources for        interference measurement.

2. CSI Reporting

Time and frequency resources available for the UE to report CSI arecontrolled by the BS.

For a CQI, a PMI, a CSI-RS resource indicator (CRI), an SSB resourceindicator (SSBRI), a layer indicator (LI), an RI, and an RSRP, the UEreceives RRC signaling including N≥1 CSI-ReportConfig reportingsettings, M≥1 CSI-ResourceConfig resource settings, and one or two listsof trigger states (given by aperiodicTriggerStateList andsemiPersistentOnPUSCH-TriggerStateList). Each trigger state inaperiodicTriggerStateList includes a list of associatedCSI-ReportConfigs indicating resource set IDs for a channel andoptionally for interference. Each trigger state insemiPersistentOnPUSCH-TriggerStateList contains one associatedCSI-ReportConfig

That is, the UE transmits a CSI report indicated by CSI-ReportConfigsassociated with a corresponding CSI-RS resource setting to the BS. Forexample, the UE may report at least one of a CQI, a PMI, a CRI, anSSBRI, an LI, an RI, or an RSRP as indicated by CSI-ReportConfigsassociated with the CSI resource setting. However, if CSI-ReportConfigsassociated with the CSI resource setting indicates ‘none’, the UE maynot report CSI or an RSRP associated with the CSI resource setting. TheCSI resource setting may indicate resources for an SS/PBCH block.

DL Channel Structures

An eNB transmits related signals on later-described DL channels to a UE,and the UE receives the related signals on the DL channels from the eNB.

(1) Physical Downlink Shared Channel (PDSCH)

The PDSCH delivers DL data (e.g., a DL-shared channel transport block(DL-SCH TB)) and adopts a modulation scheme such as quadrature phaseshift keying (QPSK), 16-ary quadrature amplitude modulation (16 QAM),64-ary QAM (64 QAM), or 256-ary QAM (256 QAM). A TB is encoded to acodeword. The PDSCH may deliver up to two codewords. The codewords areindividually subjected to scrambling and modulation mapping, andmodulation symbols from each codeword are mapped to one or more layers.An OFDM signal is generated by mapping each layer together with a DMRSto resources, and transmitted through a corresponding antenna port.

(2) Physical Downlink Control Channel (PDCCH)

The PDCCH delivers DCI and adopts QPSK as a modulation scheme. One PDCCHincludes 1, 2, 4, 8, or 16 control channel elements (CCEs) according toits aggregation level (AL). One CCE includes 6 resource element groups(REGs), each REG being defined by one OFDM symbol by one (physical)resource block ((P)RB)).

FIG. 16 illustrates an exemplary structure of one REG. In FIG. 16, Drepresents an RE to which DCI is mapped, and R represents an RE to whicha DMRS is mapped. The DMRS is mapped to RE #1, RE #5, and RE #9 alongthe frequency direction in one symbol.

The PDCCH is transmitted in a control resource set (CORESET). A CORESETis defined as a set of REGs with a given numerology (e.g., an SCS, a CPlength, or the like). A plurality of CORESETs for one UE may overlapwith each other in the time/frequency domain. A CORESET may beconfigured by system information (e.g., a master information block(MIB)) or UE-specific higher-layer signaling (e.g., RRC signaling).Specifically, the number of RBs and the number of symbols (3 at maximum)in the CORESET may be configured by higher-layer signaling.

For each CORESET, a precoder granularity in the frequency domain is setto one of the followings by higher-layer signaling:

-   -   sameAsREG-bundle: It equals to an REG bundle size in the        frequency domain.    -   allContiguousRBs: It equals to the number of contiguous RBs in        the frequency domain within the CORESET.

The REGs of the CORESET are numbered in a time-first mapping manner.That is, the REGs are sequentially numbered in an ascending order,starting from 0 for the first OFDM symbol of the lowest-numbered RB inthe CORESET.

CCE-to-REG mapping for the CORESET may be an interleaved type or anon-interleaved type. FIG. 17(a) is an exemplary view illustratingnon-interleaved CCE-REG mapping, and FIG. 17(b) is an exemplary viewillustrating interleaved CCE-REG mapping.

-   -   Non-interleaved CCE-to-REG mapping (or localized CCE-to-REG        mapping): 6 REGs for a given CCE are grouped into one REG        bundle, and all of the REGs for the given CCE are contiguous.        One REG bundle corresponds to one CCE.    -   Interleaved CCE-to-REG mapping (or distributed CCE-to-REG        mapping): 2, 3 or 6 REGs for a given CCE are grouped into one        REG bundle, and the REG bundle is interleaved in the CORESET. In        a CORESET including one or two OFDM symbols, an REG bundle        includes 2 or 6 REGs, and in a CORESET including three OFDM        symbols, an REG bundle includes 3 or 6 REGs. An REG bundle size        is configured on a CORESET basis.

FIG. 18 illustrates an exemplary block interleaver. For the aboveinterleaving operation, the number A of rows in a (block) interleaver isset to one or 2, 3, and 6. When the number of interleaving units for agiven CORESET is P, the number of columns in the block interleaver isP/A. In the block interleaver, a write operation is performed in arow-first direction, and a read operation is performed in a column-firstdirection, as illustrated in FIG. 18. Cyclic shift (CS) of aninterleaving unit is applied based on an ID which is configurableindependently of a configurable ID for the DMRS.

The UE acquires DCI delivered on a PDCCH by decoding (so-called blinddecoding) a set of PDCCH candidates. A set of PDCCH candidates decodedby a UE are defined as a PDCCH search space set. A search space set maybe a common search space or a UE-specific search space. The UE mayacquire DCI by monitoring PDCCH candidates in one or more search spacesets configured by an MIB or higher-layer signaling. Each CORESETconfiguration is associated with one or more search space sets, and eachsearch space set is associated with one CORESET configuration. Onesearch space set is determined based on the following parameters.

-   -   controlResourceSetId: A set of control resources related to the        search space set.    -   monitoringSlotPeriodicityAndOffset: A PDCCH monitoring        periodicity (in slots) and a PDCCH monitoring offset (in slots).    -   monitoringSymbolsWithinSlot: A PDCCH monitoring pattern (e.g.,        the first symbol(s) in the CORESET) in a PDCCH monitoring slot.    -   nrofCandidates: The number of PDCCH candidates (one of 0, 1, 2,        3, 4, 5, 6, and 8) for each AL={1, 2, 4, 8, 16}.

[Table 8] lists exemplary features of the respective search space types.

TABLE 8 Search Type Space RNTI Use Case Type0- Common SI-RNTI on a SIBPDCCH primary cell Decoding Type0A- Common SI-RNTI on a SIB PDCCHprimary cell Decoding Type1- Common RA-RNTI or TC- Msg2, PDCCH RNTI on aprimary Msg4 cell decoding in RACH Type2- Common P-RNTI on a PagingPDCCH primary cell Decoding Type3- Common INT-RNTI, SFI- PDCCH RNTI,TPC- PUSCH-RNTI, TPC-PUCCH- RNTI, TPC-SRS- RNTI, C-RNTI, MCS-C-RNTI, orCS-RNTI(s) UE C-RNTI, or MCS- User Specific C-RNTI, or specificCS-RNTI(s) PDSCH decoding

[Table 9] lists exemplary DCI formats transmitted on the PDCCH.

TABLE 9 DCI format Usage 0_0 Scheduling of PUSCH in one cell 0_1Scheduling of PUSCH in one cell 1_0 Scheduling of PDSCH in one cell 1_1Scheduling of PDSCH in one cell 2_0 Notifying a group of UEs of the slotformat 2_1 Notifying a group of UEs of the PRB(s) and OFDM symbol(s)where UE may assume no transmission is intended for the UE 2_2Transmission of TPC commands for PUCCH and PUSCH 2_3 Transmission of agroup of TPC commands for SRS transmissions by one or more UEs

DCI format 0_0 may be used to schedule a TB-based (or TB-level) PUSCH,and DCI format 0_1 may be used to schedule a TB-based (or TB-level)PUSCH or a code block group (CBG)-based (or CBG-level) PUSCH. DCI format1_0 may be used to schedule a TB-based (or TB-level) PDSCH, and DCIformat 1_1 may be used to schedule a TB-based (or TB-level) PDSCH or aCBG-based (or CBG-level) PDSCH. DCI format 2_0 is used to deliverdynamic slot format information (e.g., a dynamic slot format indicator(SFI)) to a UE, and DCI format 2_1 is used to deliver DL pre-emptioninformation to a UE. DCI format 2_0 and/or DCI format 2_1 may bedelivered to a corresponding group of UEs on a group common PDCCH whichis a PDCCH directed to a group of UEs.

UL Channel Structure

A UE transmits signals over the following UL channels to a BS. In otherwords, the BS receives the signals from the UE over the following ULchannels.

(1) Physical Uplink Shared Channel (PUSCH)

The PUSCH carries UL data (e.g., UL-shared channel transport block(UL-SCH TB)) and/or UCI. The PUSCH is transmitted based on a cyclicprefix orthogonal frequency division multiplexing (CP-OFDM) waveform ora discrete Fourier transform spread orthogonal frequency divisionmultiplexing (DFT-s-OFDM) waveform. When the PUSCH is transmitted in theDFT-s-OFDM waveform, the UE transmits the PUSCH by applying transformprecoding. For example, when transform precoding is disabled, the UE maytransmit the PUSCH in the CP-OFDM waveform. When transform precoding isenabled, the UE may transmit the PUSCH in the CP-OFDM or DFT-s-OFDMwaveform. The PUSCH transmission may be dynamically scheduled by a ULgrant in DCI. Alternatively, the PUSCH transmission may besemi-statically scheduled by higher layer signaling (e.g., RRCsignaling) (and/or Layer 1 (L1) signaling (e.g., PDCCH) (configuredgrant). Both codebook based PUSCH transmission and non-codebook basedPUSCH transmission may be allowed.

(2) Physical Uplink Control Channel (PUCCH)

The PUCCH carries UCI, a HARQ-ACK, and/or an SR. Depending on thetransmission duration of the PUCCH, the PUCCH is classified into a shortPUCCH and a long PUCCH. Table 10 shows PUCCH formats.

TABLE 10 Length in OFDM PUCCH symbols Number format N_(symb) ^(PUCCH) ofbits Usage Etc 0 1-2 ≤2 HARQ, SR Sequence selection 1  4-14 ≤2 HARQ,[SR] Sequence selection 2 1-2 >2 HARQ, CSI, [SR] CP-OFDM 3  4-14 >2HARQ, CSI, [SR] DFT-s-OFDM (no UE multiplexing) 4  4-14 >2 HARQ, CSI,[SR] DFT-s-OFDM (Pre DFT OCC)

PUCCH format 0 conveys UCI of up to 2 bits and is mapped in asequence-based manner, for transmission. Specifically, the UE transmitsspecific UCI to the BS by transmitting one of a plurality of sequenceson a PUCCH of PUCCH format 0. Only when the UE transmits a positive SR,the UE transmits the PUCCH of PUCCH format 0 in PUCCH resources for acorresponding SR configuration.

PUCCH format 1 conveys UCI of up to 2 bits and modulation symbols of theUCI are spread with an orthogonal cover code (OCC) (which is configureddifferently whether frequency hopping is performed) in the time domain.The DMRS is transmitted in a symbol in which a modulation symbol is nottransmitted (i.e., transmitted in time division multiplexing (TDM)).

PUCCH format 2 conveys UCI of more than 2 bits and modulation symbols ofthe DCI are transmitted in frequency division multiplexing (FDM) withthe DMRS. The DMRS is located in symbols #1, #4, #7, and #10 of a givenRB with a density of ⅓. A pseudo noise (PN) sequence is used for a DMRSsequence. For 2-symbol PUCCH format 2, frequency hopping may beactivated

PUCCH format 3 does not support UE multiplexing in the same PRBS, andconveys UCI of more than 2 bits. In other words, PUCCH resources ofPUCCH format 3 do not include an OCC. Modulation symbols are transmittedin TDM with the DMRS.

PUCCH format 4 supports multiplexing of up to 4 UEs in the same PRBS,and conveys UCI of more than 2 bits. In other words, PUCCH resources ofPUCCH format 3 include an OCC. Modulation symbols are transmitted in TDMwith the DMRS.

Discontinuous Reception (DRX)

A UE may perform a DRX operation in the afore-described/proposedprocedures and/or methods. A UE configured with DRX may reduce powerconsumption by receiving a DL signal discontinuously. DRX may beperformed in an RRC_IDLE state, an RRC_INACTIVE state, and anRRC_CONNECTED state. The UE performs DRX to receive a paging signaldiscontinuously in the RRC_IDLE state and the RRC_INACTIVE state. DRX inthe RRC_CONNECTED state (RRC_CONNECTED DRX) will be described below.

FIG. 19 illustrates a DRX cycle (in the RRC_CONNECTED state).

Referring to FIG. 19, a DRX cycle includes an On Duration and anOpportunity for DRX. The DRX cycle defines the time interval betweenperiodic repetitions of the On Duration. The On Duration is a timeperiod during which the UE monitors a PDCCH. When the UE is configuredwith DRX, the UE performs PDCCH monitoring during the On Duration. Whenthe UE successfully detects a PDCCH during the PDCCH monitoring, the UEstarts an inactivity timer and is kept awake. On the contrary, when theUE fails in detecting any PDCCH during the PDCCH monitoring, the UEtransitions to a sleep state after the On Duration. Accordingly, whenDRX is configured, PDCCH monitoring/reception may be performeddiscontinuously in the time domain in the afore-described/proposedprocedures and/or methods. For example, when DRX is configured, PDCCHreception occasions (e.g., slots with PDCCH search spaces) may beconfigured discontinuously according to a DRX configuration in thepresent disclosure. On the contrary, when DRX is not configured, PDCCHmonitoring/reception may be performed continuously in the time domain.For example, when DRX is not configured, PDCCH reception occasions(e.g., slots with PDCCH search spaces) may be configured continuously inthe present disclosure. Irrespective of whether DRX is configured, PDCCHmonitoring may be restricted during a time period configured as ameasurement gap.

Table 11 describes a DRX operation of a UE (in the RRC_CONNECTED state).

Referring to Table U1, DRX configuration information is received byhigher-layer signaling (e.g., RRC signaling), and DRX ON/OFF iscontrolled by a DRX command from the MAC layer. Once DRX is configured,the UE may perform PDCCH monitoring discontinuously in performing theafore-described/proposed procedures and/or methods, as illustrated inFIG. 19.

TABLE 11 Type of signals UE procedure 1 st step RRC signalling(MAC-Receive DRX configuration CellGroupConfig) information 2 nd Step MACCE((Long) DRX Receive DRX command command MAC CE) 3 rd Step — Monitor aPDCCH during an On Duration of a DRX cycle

MAC-CellGroupConfig contains configuration information required toconfigure MAC parameters for a cell group. MAC-CellGroupConfig may alsocontain DRX configuration information. For example, MAC-CellGroupConfigmay contain the following information for defining DRX.-Value ofdrx-onDurationTimer: Defines the duration of a time period at thebeginning of a DRX cycle.

-   -   Value of drx-InactivityTimer: Defines the duration of a time        period during which the UE is awake after a PDCCH occasion in        which a PDCCH indicates an initial UL or DL user data        transmission for the UE.    -   Value of drx-HARQ-RTT-TimerDL: Defines the duration of a maximum        time period until a DL retransmission is received after        reception of a DL initial transmission.    -   Value of drx-HARQ-RTT-TimerDL: Defines the duration of a maximum        time period until a grant for a UL retransmission is received        after reception of a grant for a UL initial transmission.    -   drx-LongCycleStartOffset: Defines the duration and starting time        of a DRX cycle.    -   drx-ShortCycle (optional): Defines the duration of a short DRX        cycle.

When any one of drx-OnDurationTimer, drx-InactivityTimer,drx-HARQ-RTT-TimerDL, and drx-HARQ-RTT-TimerDL is running, the UEperforms PDCCH monitoring in each PDCCH occasion, staying in the awakestate.

In NR, the CSI-RS may be used for multiple purposes. For example, theCSI-RS may be used as/for a beam management (BM) reference signal(BM-RS), a beam failure detection (BFD) reference signal (BFD-RS), atracking reference signal (TRS), a radio resource management (RRM)measurement reference signal (RRM-RS), a radio link monitoring (RLM)reference signal (RLM-RS), CSI acquisition, and so on.

Accordingly, the CSI-RS has been designed such that the CSI-RS iscapable of being configured flexibly. In addition, since a bandwidthpart (BWP), which is configured for each system bandwidth and each UE,covers not only a narrowband of about 5 MHz but also a wideband of 100MHz or above, a wideband CSI-RS may be configured according to operatingenvironments. In particular, considering that the CSI-RS is defined as asignal for measuring channel quality, channel characteristics may beobtained over the entire frequency band if the CSI-RS is transmitted inall frequency bands occupied by the UE.

However, when one service provider manages an NR system operating in anunlicensed band (NR-U system), the NR-U system managed by the serviceprovider may simultaneously operate in the same band as other systemssuch as Wi-Fi, or Licensed Assisted Access (LAA) systems or other NR-Usystems managed by other service providers, unlike licensed-bandsystems. For coexistence between systems operating in an unlicensedband, such a system performs channel clearance assessment (CCA)operation to determine whether a channel for signal transmission isoccupied by other systems before performing the signal transmission.

That is, a signal is transmitted only when it is determined by the CCAthat a frequency band to be used for the signal transmission is idle.Regarding the CCA for the wideband CSI-RS, it may be considered that theRLM-RS is used to determine whether a channel is busy or idle for theentire system bandwidth used by the UE.

However, a frequency band used for the NR-U system is generally expectedto be greater than a basic frequency band used for the legacy systemsuch as Wi-Fi. For example, if the NR system operates in an unlicensedband of which the bandwidth is 80 MHz and a system such as Wi-Fi or LAAoperates in a bandwidth of 20 MHz as shown in FIG. 22, the probabilitythat a channel is determined to be busy by CCA operation performed for80 MHz may increase significantly. In particular, when a signal isperiodically transmitted, if the probability that a channel isdetermined to be busy increases, signal transmission failure is highlylikely to occur during a time allocated for the transmission.

When the bandwidth of a channel or signal to be transmitted is greaterthan that of an LBT sub-band (e.g., a sub-band with a bandwidth of 20MHz), transmitting the corresponding channel only in an LBT sub-bandwhere the channel is determined to be idle may be discussed for datachannels.

In the case of the CSI-RS, i.e., a signal for channel qualitymeasurement, if the CSI-RS is transmitted in a partial band, there maybe a problem that channel information is not valid for the entirefrequency band. For example, when the CSI-RS is transmitted in a secondsub-band shown in FIG. 20, the channel quality estimated based on theCSI-RS may not be valid for the entire 80 MHz band.

When the CSI-RS is used as the BM-RS, BFD-RS, RRM-RS, or RLM-RS, it maybe considered that one or more sub-bands validly represent the entirefrequency band. However, in the case of CSI, the data rate of a datachannel transmitted over the entire frequency band may not be configuredbased on information about a part of the entire frequency band. When thechannel quality for the entire frequency band is reported withoutdetermining whether the CSI-RS is transmitted, the channel quality maybe erroneous so that user throughput may be significantly degraded.

The present disclosure provides a method of efficiently measuring achannel state information-reference signal (CSI-RS) and reporting themeasurement, when a system band or BWP band larger than a frequency bandfor CCA (hereinafter, referred to as “LBT subband”) is configured byreflecting the above features.

FIGS. 21, 22 and 23 are diagrams illustrating an implementation exampleof a UE, a BS, and a network according to an embodiment of the presentdisclosure.

Referring to FIG. 21, the BS according to the present disclosure mayperform CCA for a CSI-RS bandwidth (S2101). The CSI-RS bandwidth mayinclude a plurality of LBT subbands, and the BS may perform CCA for eachindividual LBT subband.

The BS may transmit a CSI-RS in at least one LBT subband based on theresult of the CCA (S2103). The CSI-RS may be a non-zero power (NZP)CSI-RS or a zero power (ZP) CSI-RS. The BS may receive, from the UE, CSImeasured based on the transmitted CSI-RS (S2105). The CSI may bemeasured based on Embodiment 1 to Embodiment 4 which will be describedlater.

The BS of FIG. 21 may be one of various wireless devices illustrated inFIGS. 26, 27 and 28. For example, the BS of FIG. 21 may be a secondwireless device 200 illustrated in FIG. 26 or a wireless device 100 or200 illustrated in FIG. 27.

Referring to FIG. 22, the UE according to the present disclosure mayreceive a CSI-RS in at least one of a plurality of LBT subbands includedin a CSI-RS bandwidth (S2201). The CSI-RS may be an NZP CSI-RS or a ZPCSI-RS.

The UE may measure CSI based on the received CSI-RS (S2203).Specifically, the CSI may be measured based on Embodiment 1 toEmbodiment 4. The UE may transmit the measured CSI to the BS (S2205).

The UE of FIG. 22 may be one of the various wireless devices illustratedin FIGS. 26, 27 and 28. For example, the UE of FIG. 22 may be a firstwireless device 100 illustrated in FIG. 26 or the wireless device 100 or200 illustrated in FIG. 27.

Referring to FIG. 23, the BS may perform CCA for a CSI-RS bandwidth(S2301). The CSI-RS bandwidth may include a plurality of LBT subbands,and the BS may perform CCA for each individual LBT subband.

The BS may transmit a CSI-RS in at least one LBT subband based on theresult of the CCA (S2303). The CSI-RS may be an NZP CSI-RS or a ZPCSI-RS. The UE may measure CSI based on the CSI-RS received in stepS2303 (S2305). Specifically, the CSI may be measured based on Embodiment1 to Embodiment 4. The UE may transmit the measured CSI to the BS(S2307).

Embodiment 1: Interference Measurement Using NZP CSI-RS

In the NR system, the BS may transmit an NZP CSI-RS for interferencemeasurement for use in CSI measurement in multi user-multiple inputmultiple output (MU-MIMO). The UE may estimate intra-cell interferenceusing the NZP CSI-RS and measure and report CSI based on the estimation.

Additionally, for transmission of a broadband signal in an unlicensedband, the BS may boost the power of the signal in a specific subbandwhen the BS determines that the channel of the specific subband is notbusy through CCA. The specific subband may be an LBT subband or acarrier-aggregated component carrier.

Accordingly, when an NZP CSI-RS is transmitted in the specific subband,it is preferable in terms of implementation ease to boost the power ofthe NZP CSI-RS together with another signal or channel However, when thetransmission power of an interference signal for CSI measurement ischanged in each time occasion for NZP CSI-RS transmission, thereliability of CSI measured based on the NZP CSI-RS may be lowered.Therefore, when the transmission power of the NZP CSI-RS is variable ineach time occasion, the following methods may be considered for CSIresource configuration or CSI measurement.

(1) Embodiment 1-1

When the strength of interference is changed in view of a change intransmission power, not channel characteristics in a CSI measurementstep, filtering for each of a plurality of time occasions to calculate ameasurement value may decrease the reliability of CSI measurement. Inthis case, the strength of an interference signal may be measured in anNZP CSI-RS in the latest one of valid resources for NZP CSI-RStransmission, for CSI measurement. For example, when a plurality of NZPCSI-RSs are allocated in one time occasion, all of the NZP CSI-RSs inthe time occasion may be used to estimate an interference signal. When aplurality of NZP CSI-RSs are allocated over a plurality of timeoccasions, the NZP CSI-RSs may be transmitted with differenttransmission power in the respective time occasions, and thus aninterference signal may be measured in an NZP CSI-RS in the latest oftime occasions to which valid NZP CSI-RSs have been allocated. Ingeneral, one time occasion may correspond to a transmission opportunity(TxOP). The TxOP may refer to a predetermined period during which accessto a specific channel is allowed without contention, for fair resourcedistribution. For example, the TxOP may refer to a period which isconfigured for a specific node to use for signal transmission from atime when a channel is determined to be idle.

(2) Embodiment 1-2

When the BS transmits an NZP CSI-RS by power boosting, the BS maytransmit information about the power-boosted NZP CSI-RS in a specificslot to the UE. When the UE is notified that power boosting is appliedto the NZP CSI-RS transmission, the UE may estimate the strength of aninterference signal and measure CSI by reflecting the power boosting inthe CSI measurement step.

(3) Embodiment 1-3

Even though an NZP CSI-RS corresponding to a signal component and an NZPCSI-RS corresponding to an interference component are transmitted basedon the same boosting in the same TxOP or slot in the CSI measurementstep, CSI may be measured without any additional operation. In thiscase, however, at least a signal component for CSI measurement and anintra-cell interference component may be filtered using resources of theTxOP or the slot, whereas any other area than the resource area may notbe filtered. This operation may be applied only to the NZ CSI-RS, whilea separate operation may be defined for the ZP CSI-RS.

On the contrary, when the NZP CSI-RS corresponding to a signal componentand the NZP-CSI-RS corresponding to an interference component are nottransmitted in the same TxOP, the UE may not update CSI, or the UE maymeasure CSI by updating only one of the signal component and theinterference component.

When the UE is configured to update only one component, (1) the UE mayupdate one of the signal component and the interference component, whichexists in the latest TxOP at a CSI measurement time or 2) only an NZPCSI-RS corresponding to one component exists in one TxOP, a component tobe updated may be predefined or configured for the UE by the BS.

For example, referring to FIG. 24, in the case where it is configuredthat only a signal component is updated, when both a CSI-RScorresponding to the signal component and a CSI-RS corresponding to aninterference component are transmitted in a TxOP (in a square box inFIG. 24) closest to a first update time, both CSI measured based on thesignal component and CSI measured based on the interference componentmay be updated. When only the CSI-RS corresponding to the signalcomponent is transmitted in a TxOP closest to a second update time, onlyCSI measured based on the signal component may be updated at the secondupdate time. However, when only the CSI-RS corresponding to theinterference component is transmitted in a closest TxOP, CSI may not beupdated at an update time such as a third update time.

In Embodiment 1, power to which the transmission power of a CSI-RS isboosted may be determined according to the number of LBT subbandscarrying the CSI-RS among a plurality of LBT subbands. For example, whena total CSI-RS bandwidth includes four LBT subbands and two of the LBTsubbands carry the CSI-RS, transmission power allocated to the four LBTsubbands may be divided into halves, which may be allocated respectivelyto the LBT subbands carrying the CSI-RS. In this case, the transmissionpower allocated to one LBT subband may be doubled, compared to the caseof transmitting the CSI-RS in the total four LBT bands.

Embodiment 2: LBT for ZP CSI-RS

In general, it may be determined whether to transmit a signal havingnon-zero power (e.g., NZP CSI-RS), after CCA. In contrast, because a ZPCSI-RS is transmitted with nulled transmission power in a specificresource, there may be no need for determining whether to transmit theZP CSI-RS regardless of a CCA result.

However, when a channel is determined to be busy as a result of CCA,this means that a current NR U-band system has not occupied the channelin view of another system. If the channel is busy, a data channel maynot be transmitted. Therefore, interference measurement using the ZPCSI-RS and CSI measurement based on the interference measurement may notreflect the channel state of the data channel

Accordingly, when transmitting the ZP CSI-RS, the BS preferablyindicates to the UE that a serving cell operating the NR U-band hasoccupied the channel or has not occupied the channel due to anothersystem. For this purpose, a method of explicitly indicating that a ZPCSI-RS transmission is currently valid by a BS is required. Thefollowing methods may be considered for the explicit indication.

1-1) Information indicating that interference measurement in the ZPCSI-RS is valid may be transmitted on a group common-physical downlinkcontrol channel (GC-PDCCH) or in an initialization signal. Whendetermining that the corresponding cell is occupying the channel or whendetermining that the channel is idle through LBT in spite of the absenceof a channel to be transmitted, the BS may determine that interferencemeasurement in the ZP CSI-RS is valid.

1-2) The ZP CSI-RS and the NZP CSI-RS may be allocated in the same area.

1-3) The ZP CSI-RS may be transmitted only in a TxOP. That is, the UEmay measure interference only when the system connected to the UE isoccupying the channel. In this case, the BS may transmit informationabout the TxOP to all UEs configured with the ZP CSI-RS.

The BS may indicate to the UE whether information related to the ZPCSI-RS is valid on an LBT subband basis. That is, when the BS indicatesto the UE that the ZP CSI-RS is not valid in a specific LBT subband, theUE may not measure interference in the LBT subband and calculate CSI fora CSI subband associated with the LBT subband. This is because when theZP CSI-RS is not valid, there is no interference information about theZP CSI-RS and thus CSI may not be calculated.

In this case, when the ZP CSI-RS is not valid, it may be defined orconfigured that CSI is calculated using an interference component in thefollowing methods.

2-1) The latest instantaneous value or average value of interferencecomponents previously measured within a specific time may be used forCSI calculation.

2-2) An interference component may be derived from the average value ofLBT subbands carrying a valid ZP CSI-RS, and CSI may be calculated basedon the interference component.

2-3) A UE, which is capable of deriving an interference component byCSI-RS subtraction, may directly measure an interference component in anNZP CSI-RS resource and use the measurement for CSI calculation.

2-4) In the absence of any BS operated by the same operator in theneighborhood, a default interference value may be preconfigured and CSImay be calculated based on the default interference value.

Further, in the case where the validity of an interference signal isdetermined, when at least one of a plurality of LBT subbands is notvalid, the statistics of the interference component may be determined tobe invalid. In other words, only when all LBT subbands are valid, thestatistics of the interference component may be determined to be valid.In this case, the afore-described CSI calculation methods in 2-1) to2-4) may also be applied.

Embodiment 3: Filtering for CSI/RRM Measurement

When the signal power of a CSI-RS or the like is measured for CSImeasurement or RRM measurement, the measurement accuracy may beincreased by filtering values measured along the time axis according tochannel characteristics or system operation characteristics. However,the use of filtering requires the premise that a CSI-RS is transmittedwith the same power in each time occasion.

Particularly when the NR U-band system operates in a wideband unlicensedband and the channel is busy in a specific LBT subband, it is preferableto transmit the CSI-RS only in some LBT subbands, and thus thetransmission power of an LBT subband available for transmission may beboosted. However, to perform filtering during boosting of thetransmission power, the UE should have knowledge of information aboutthe transmission power boosting and the LBT-subband carrying the CSI-RS.Therefore, the BS may indicate the information to the UE, and anoperation based on the information may be defined.

Regarding RRM measurement, the UE generally increases measurementaccuracy by filtering, and thus it is necessary to define a method ofindicating a time of transmitting a CSI-RS or synchronization signalblock (SSB) and an LBT subband carrying the CSI-RS or the SSB. Forexample, the BS may directly indicate to the UE whether transmissionpower is uniform on a Tx burst basis in an SSB or CSI-RS-based RRMmeasurement configuration step. A Tx burst refers to a time periodduring which DL signals are transmitted or a bundle of DL signals, and aTxOP may be an example of the Tx burst.

For example, when transmission power is not uniform over Tx bursts, theUE may measure the reception power of each Tx burst and use the latestmeasured reception power value in measurement reporting or eventtriggering. Further, in the case of RRM measurement, the BS indicates anL3 filtering value for L3 filtering. When the L3 filtering value is 1,this may be interpreted as indicating that Layer 1 filtering is notperformed either in the unlicensed band. Further, when the L3 filtervalue is 1, this may mean that only a current filtering value is used.

Embodiment 3 may be applicable to noise/interference measurement using aZP CSI-RS or an NZP CSI-RS.

Embodiment 4: CSI Reference Resource

In the NR system, a CSI reference resource for indicating CSI reportingis defined as follows.

The CSI reference resource is defined by a DL PRB group related tocalculated CSI in the frequency domain.

In the time domain, a CSI reference resource for CSI reporting in a ULslot n′ is defined as a single DL slot n-nCSI_ref.

$n = \left\lfloor {n^{\prime} \cdot \frac{2^{\mu_{DL}}}{2^{\mu_{UL}}}} \right\rfloor$

where μ_(α) and μ_(UL) may represent a DL SCS and a UL SCS,respectively.

In periodic or semi-persistent CSI reporting, once a single CSI-RSresource is configured for channel measurement, nCSI_ref should be thesmallest of numbers equal to or larger than 4*2uDL, and a configuredreference resource should be a valid DL slot.

Further, when multiple CSI-RS resources are configured for channelmeasurement, nCSI_ref should be the smallest of numbers equal to orlarger than 5*2uDL, and a configured reference resource should be avalid DL slot.

In aperiodic CSI reporting, when it is indicated to the UE that CSI isto be reported in the same slot as carrying a CSI request, nCSI_refrepresents a reference resource in the same valid DL slot as carryingthe CSI request. Otherwise, nCSI_ref is determined by └Z′/N_(symb)^(slot)┘ where Z′ represents a latency requirement, and nCSI_refrepresents a valid DL slot.

When a periodic or semi-persistent CSI-RS/CSI-IM or SSB is used forchannel measurement and/or interference measurement, the UE may expectnot to perform channel/interference measurement in Z′ symbols from thelast OFDM symbol of the CSI-RS/CSI-IM/SSB before a transmission time ofthe first OFDM symbol for aperiodic CSI reporting.

Among the slots of the serving cell, slots which are configured toinclude DL symbols or flexible symbols by a higher layer and which donot correspond to a measurement gap are regarded as valid slots.

However, when a wideband CSI-RS is transmitted in the unlicensed band,the CSI-RS may be transmitted only in some LBT subbands. In this case,it may be necessary to change the method of determining a CSI referenceresource or to change a CSI reference resource. For example, a CSIreference resource for the unlicensed band may be defined as follows.

(1) Embodiment 4-1: CSI Reference Resource in Frequency Domain

When a wideband CSI-RS is transmitted or a CSI-RS is transmitted inwideband over a plurality of CSI-RS resources, the BS may indicate LBTsubbands or CSI-RS resources carrying the CSI-RS to the UE. Based onthis, a resource known as carrying the CSI-RS in the frequency domainand a resource used to calculate a CSI value based on the resource maybe defined as a CSI reference resource. Alternatively, when it isindicated that all LBT subbands corresponding to a specific CSI-RSresource have been transmitted in the frequency domain, all of the LBTsubbands may be defined as a valid CSI reference resource.

(2) Embodiment 3-2: CSI Reference Resource in Time Domain

It may be difficult to expect that a CSI-RS is stably transmitted in anarea other than a Tx burst occupied by the BS. Therefore, for stableCSI-RS reception, only CSI-RS resources within the Tx burst occupied bythe BS are preferably used as effective CSI resources. Therefore, whenthe CSI reference resource defined in the NR system is applied, thedefinition of the CSI reference resource is preferably applied only to aslot including the CSI-RS resources of the Tx burst. In other words,when there is no valid DL slot in a specific Tx burst, all slots of theTx burst may be defined as invalid DL slots. Additionally, whenmeasurement restriction is set, a specific slot included in the latestTX burst including the CSI reference resource may be defined as a validDL slot. For example, DL slots or flexible slots included in the latestTx burst may be defined as valid DL slots, among DL slots or flexibleslots that match the definition of an effective DL slot in the NRsystem.

The various descriptions, functions, procedures, proposals, methods,and/or operation flowcharts of the present disclosure described hereinmay be applied to, but not limited to, various fields requiring wirelesscommunication/connectivity (e.g., 5G) between devices.

More specific examples will be described below with reference to thedrawings. In the following drawings/description, like reference numeralsdenote the same or corresponding hardware blocks, software blocks, orfunction blocks, unless otherwise specified.

FIG. 25 illustrates a communication system 1 applied to the presentdisclosure.

Referring to FIG. 25, the communication system 1 applied to the presentdisclosure includes wireless devices, BSs, and a network. A wirelessdevice is a device performing communication using radio accesstechnology (RAT) (e.g., 5G NR (or New RAT) or LTE), also referred to asa communication/radio/5G device. The wireless devices may include, notlimited to, a robot 100 a, vehicles 100 b-1 and 100 b-2, an extendedreality (XR) device 100 c, a hand-held device 100 d, a home appliance100 e, an IoT device 100 f, and an artificial intelligence (AI)device/server 400. For example, the vehicles may include a vehiclehaving a wireless communication function, an autonomous driving vehicle,and a vehicle capable of vehicle-to-vehicle (V2V) communication. Herein,the vehicles may include an unmanned aerial vehicle (UAV) (e.g., adrone). The XR device may include an augmented reality (AR)/virtualreality (VR)/mixed reality (MR) device and may be implemented in theform of a head-mounted device (HMD), a head-up display (HUD) mounted ina vehicle, a television (TV), a smartphone, a computer, a wearabledevice, a home appliance, a digital signage, a vehicle, a robot, and soon. The hand-held device may include a smartphone, a smart pad, awearable device (e.g., a smart watch or smart glasses), and a computer(e.g., a laptop). The home appliance may include a TV, a refrigerator, awashing machine, and so on. The IoT device may include a sensor, a smartmeter, and so on. For example, the BSs and the network may beimplemented as wireless devices, and a specific wireless device 200 amay operate as a BS/network node for other wireless devices.

The wireless devices 100 a to 100 f may be connected to the network 300via the BSs 200. An AI technology may be applied to the wireless devices100 a to 100 f, and the wireless devices 100 a to 100 f may be connectedto the AI server 400 via the network 300. The network 300 may beconfigured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g.,NR) network. Although the wireless devices 100 a to 100 f maycommunicate with each other through the BSs 200/network 300, thewireless devices 100 a to 100 f may perform direct communication (e.g.,SL communication) with each other without intervention of theBSs/network. For example, the vehicles 100 b-1 and 100 b-2 may performdirect communication (e.g. V2V/vehicle-to-everything (V2X)communication). The IoT device (e.g., a sensor) may perform directcommunication with other IoT devices (e.g., sensors) or other wirelessdevices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b, and 150 c may beestablished between the wireless devices 100 a to 100 f/BS 200 andbetween the BSs 200. Herein, the wireless communication/connections maybe established through various RATs (e.g., 5G NR) such as UL/DLcommunication 150 a, SL communication 150 b (or, D2D communication), orinter-BS communication (e.g. relay or integrated access backhaul (IAB)).Wireless signals may be transmitted and received between the wirelessdevices, between the wireless devices and the BSs, and between the BSsthrough the wireless communication/connections 150 a, 150 b, and 150 c.For example, signals may be transmitted and receive don various physicalchannels through the wireless communication/connections 150 a, 150 b and150 c. To this end, at least a part of various configuration informationconfiguring processes, various signal processing processes (e.g.,channel encoding/decoding, modulation/demodulation, and resourcemapping/demapping), and resource allocation processes, fortransmitting/receiving wireless signals, may be performed based on thevarious proposals of the present disclosure.

FIG. 26 illustrates wireless devices applicable to the presentdisclosure.

Referring to FIG. 26, a first wireless device 100 and a second wirelessdevice 200 may transmit wireless signals through a variety of RATs(e.g., LTE and NR). {The first wireless device 100 and the secondwireless device 200} may correspond to {the wireless device 100 x andthe BS 200} and/or {the wireless device 100 x and the wireless device100 x} of FIG. 25.

The first wireless device 100 may include one or more processors 102 andone or more memories 104, and further include one or more transceivers106 and/or one or more antennas 108. The processor(s) 102 may controlthe memory(s) 104 and/or the transceiver(s) 106 and may be configured toimplement the descriptions, functions, procedures, proposals, methods,and/or operation flowcharts disclosed in this document. For example, theprocessor(s) 102 may process information in the memory(s) 104 togenerate first information/signals and then transmit wireless signalsincluding the first information/signals through the transceiver(s) 106.The processor(s) 102 may receive wireless signals including secondinformation/signals through the transceiver(s) 106 and then storeinformation obtained by processing the second information/signals in thememory(s) 104. The memory(s) 104 may be connected to the processor(s)102 and may store various pieces of information related to operations ofthe processor(s) 102. For example, the memory(s) 104 may store softwarecode including instructions for performing all or a part of processescontrolled by the processor(s) 102 or for performing the descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document. The processor(s) 102 and the memory(s) 104may be a part of a communication modem/circuit/chip designed toimplement RAT (e.g., LTE or NR). The transceiver(s) 106 may be connectedto the processor(s) 102 and transmit and/or receive wireless signalsthrough the one or more antennas 108. Each of the transceiver(s) 106 mayinclude a transmitter and/or a receiver. The transceiver(s) 106 may beinterchangeably used with radio frequency (RF) unit(s). In the presentdisclosure, the wireless device may be a communicationmodem/circuit/chip.

Specifically, instructions and/or operations controlled by the processor102 and stored in the memory 104 in the first wireless device 100according to an embodiment of the present disclosure will be describedbelow.

While the following operations are described in the context of controloperations of the processor 102 from the perspective of the processor102, software code for performing these operations may be stored in thememory 104.

The processor 102 may control the transceiver 106 to receive a CSI-RS inat least one of a plurality of LBT subbands included in a CSI-RSbandwidth. The CSI-RS may be an NZP CSI-RS or ZP CSI-RS. The processor102 may measure CSI based on the received CSI-RS. A specific method ofmeasuring CSI may be based on Embodiment 1 to Embodiment 4. Theprocessor 102 may then control the transceiver 106 to transmit themeasured CSI to the second wireless device 200.

The second wireless device 200 may include one or more processors 202and one or more memories 204, and further include one or moretransceivers 206 and/or one or more antennas 208. The processor(s) 202may control the memory(s) 204 and/or the transceiver(s) 206 and may beconfigured to implement the descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument. For example, the processor(s) 202 may process information inthe memory(s) 204 to generate third information/signals and thentransmit wireless signals including the third information/signalsthrough the transceiver(s) 206. The processor(s) 202 may receivewireless signals including fourth information/signals through thetransceiver(s) 106 and then store information obtained by processing thefourth information/signals in the memory(s) 204. The memory(s) 204 maybe connected to the processor(s) 202 and store various pieces ofinformation related to operations of the processor(s) 202. For example,the memory(s) 204 may store software code including instructions forperforming all or a part of processes controlled by the processor(s) 202or for performing the descriptions, functions, procedures, proposals,methods, and/or operation flowcharts disclosed in this document. Theprocessor(s) 202 and the memory(s) 204 may be a part of a communicationmodem/circuit/chip designed to implement RAT (e.g., LTE or NR). Thetransceiver(s) 206 may be connected to the processor(s) 202 and transmitand/or receive wireless signals through the one or more antennas 208.Each of the transceiver(s) 206 may include a transmitter and/or areceiver. The transceiver(s) 206 may be interchangeably used with RFunit(s). In the present disclosure, the wireless device may be acommunication modem/circuit/chip.

Specifically, instructions and/or operations controlled by the processor202 and stored in the memory 204 in the second wireless device 200according to an embodiment of the present disclosure will be describedbelow.

While the following operations are described in the context of controloperations of the processor 202 from the perspective of the processor202, software code for performing these operations may be stored in thememory 204.

The processor 202 may perform CCA for a CSI-RS bandwidth. The CSI-RSbandwidth may include a plurality of LBT subbands. The processor 202 mayperform CCA for each of the plurality of LBT subbands.

The processor 202 may control the transceiver 206 to transmit a CSI-RSin at least one LBT subband based on the result of the CCA. The CSI-RSmay be an NZP CSI-RS or ZP CSI-RS. The processor 202 may control thetransceiver 206 to receive CSI measured based on the transmitted CSI-RSfrom the first wireless device 100. The method of measuring CSI may bebased on Embodiment 1 to Embodiment 4.

Now, hardware elements of the wireless devices 100 and 200 will bedescribed in greater detail. One or more protocol layers may beimplemented by, not limited to, one or more processors 102 and 202. Forexample, the one or more processors 102 and 202 may implement one ormore layers (e.g., functional layers such as physical (PHY), mediumaccess control (MAC), radio link control (RLC), packet data convergenceprotocol (PDCP), RRC, and service data adaptation protocol (SDAP)). Theone or more processors 102 and 202 may generate one or more protocoldata units (PDUs) and/or one or more service data Units (SDUs) accordingto the descriptions, functions, procedures, proposals, methods, and/oroperation flowcharts disclosed in this document. The one or moreprocessors 102 and 202 may generate messages, control information, data,or information according to the descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument and provide the messages, control information, data, orinformation to one or more transceivers 106 and 206. The one or moreprocessors 102 and 202 may generate signals (e.g., baseband signals)including PDUs, SDUs, messages, control information, data, orinformation according to the descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument and provide the generated signals to the one or moretransceivers 106 and 206. The one or more processors 102 and 202 mayreceive the signals (e.g., baseband signals) from the one or moretransceivers 106 and 206 and acquire the PDUs, SDUs, messages, controlinformation, data, or information according to the descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document.

The one or more processors 102 and 202 may be referred to ascontrollers, microcontrollers, microprocessors, or microcomputers. Theone or more processors 102 and 202 may be implemented by hardware,firmware, software, or a combination thereof. For example, one or moreapplication specific integrated circuits (ASICs), one or more digitalsignal processors (DSPs), one or more digital signal processing devices(DSPDs), one or more programmable logic devices (PLDs), or one or morefield programmable gate arrays (FPGAs) may be included in the one ormore processors 102 and 202. The descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument may be implemented using firmware or software, and the firmwareor software may be configured to include the modules, procedures, orfunctions. Firmware or software configured to perform the descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document may be included in the one or more processors102 and 202 or may be stored in the one or more memories 104 and 204 andexecuted by the one or more processors 102 and 202. The descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document may be implemented using firmware or softwarein the form of code, an instruction, and/or a set of instructions.

The one or more memories 104 and 204 may be connected to the one or moreprocessors 102 and 202 and store various types of data, signals,messages, information, programs, code, instructions, and/or commands Theone or more memories 104 and 204 may be configured to include read-onlymemories (ROMs), random access memories (RAMs), electrically erasableprogrammable read-only memories (EPROMs), flash memories, hard drives,registers, cash memories, computer-readable storage media, and/orcombinations thereof. The one or more memories 104 and 204 may belocated at the interior and/or exterior of the one or more processors102 and 202. The one or more memories 104 and 204 may be connected tothe one or more processors 102 and 202 through various technologies suchas wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, controlinformation, and/or wireless signals/channels, mentioned in the methodsand/or operation flowcharts of this document, to one or more otherdevices. The one or more transceivers 106 and 206 may receive user data,control information, and/or wireless signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperation flowcharts disclosed in this document, from one or more otherdevices. For example, the one or more transceivers 106 and 206 may beconnected to the one or more processors 102 and 202 and transmit andreceive wireless signals. For example, the one or more processors 102and 202 may perform control so that the one or more transceivers 106 and206 may transmit user data, control information, or wireless signals toone or more other devices. The one or more processors 102 and 202 mayperform control so that the one or more transceivers 106 and 206 mayreceive user data, control information, or wireless signals from one ormore other devices. The one or more transceivers 106 and 206 may beconnected to the one or more antennas 108 and 208 and the one or moretransceivers 106 and 206 may be configured to transmit and receive userdata, control information, and/or wireless signals/channels, mentionedin the descriptions, functions, procedures, proposals, methods, and/oroperation flowcharts disclosed in this document, through the one or moreantennas 108 and 208. In this document, the one or more antennas may bea plurality of physical antennas or a plurality of logical antennas(e.g., antenna ports). The one or more transceivers 106 and 206 mayconvert received wireless signals/channels from RF band signals intobaseband signals in order to process received user data, controlinformation, and wireless signals/channels using the one or moreprocessors 102 and 202. The one or more transceivers 106 and 206 mayconvert the user data, control information, and wirelesssignals/channels processed using the one or more processors 102 and 202from the baseband signals into the RF band signals. To this end, the oneor more transceivers 106 and 206 may include (analog) oscillators and/orfilters.

FIG. 26 illustrates another example of a wireless device applied to thepresent disclosure. The wireless device may be implemented in variousforms according to a use case/service (refer to FIG. 24).

Referring to FIG. 26, wireless devices 100 and 200 may correspond to thewireless devices 100 and 200 of FIG. 25 and may be configured to includevarious elements, components, units/portions, and/or modules. Forexample, each of the wireless devices 100 and 200 may include acommunication unit 110, a control unit 120, a memory unit 130, andadditional components 140. The communication unit 110 may include acommunication circuit 112 and transceiver(s) 114. For example, thecommunication circuit 112 may include the one or more processors 102 and202 and/or the one or more memories 104 and 204 of FIG. 25. For example,the transceiver(s) 114 may include the one or more transceivers 106 and206 and/or the one or more antennas 108 and 208 of FIG. 25. The controlunit 120 is electrically connected to the communication unit 110, thememory 130, and the additional components 140 and provides overallcontrol to the wireless device. For example, the control unit 120 maycontrol an electric/mechanical operation of the wireless device based onprograms/code/instructions/information stored in the memory unit 130.The control unit 120 may transmit the information stored in the memoryunit 130 to the outside (e.g., other communication devices) via thecommunication unit 110 through a wireless/wired interface or store, inthe memory unit 130, information received through the wireless/wiredinterface from the outside (e.g., other communication devices) via thecommunication unit 110.

The additional components 140 may be configured in various mannersaccording to type of the wireless device. For example, the additionalcomponents 140 may include at least one of a power unit/battery,input/output (I/O) unit, a driving unit, and a computing unit. Thewireless device may be implemented in the form of, not limited to, therobot (100 a of FIG. 24), the vehicles (100 b-1 and 100 b-2 of FIG. 24),the XR device (100 c of FIG. 24), the hand-held device (100 d of FIG.24), the home appliance (100 e of FIG. 24), the IoT device (100 f ofFIG. 24), a digital broadcasting terminal, a hologram device, a publicsafety device, an MTC device, a medical device, a FinTech device (or afinance device), a security device, a climate/environment device, the AIserver/device (400 of FIG. 24), the BSs (200 of FIG. 24), a networknode, or the like. The wireless device may be mobile or fixed accordingto a use case/service.

In FIG. 26, all of the various elements, components, units/portions,and/or modules in the wireless devices 100 and 200 may be connected toeach other through a wired interface or at least a part thereof may bewirelessly connected through the communication unit 110. For example, ineach of the wireless devices 100 and 200, the control unit 120 and thecommunication unit 110 may be connected by wire and the control unit 120and first units (e.g., 130 and 140) may be wirelessly connected throughthe communication unit 110. Each element, component, unit/portion,and/or module in the wireless devices 100 and 200 may further includeone or more elements. For example, the control unit 120 may beconfigured with a set of one or more processors. For example, thecontrol unit 120 may be configured with a set of a communication controlprocessor, an application processor, an electronic control unit (ECU), agraphical processing unit, and a memory control processor. In anotherexample, the memory 130 may be configured with a RAM, a dynamic RAM(DRAM), a ROM, a flash memory, a volatile memory, a non-volatile memory,and/or a combination thereof.

The implementation example of FIG. 26 will hereinafter be described withreference to the attached drawings.

FIG. 27 illustrates a vehicle or an autonomous driving vehicle appliedto the present disclosure. The vehicle or autonomous driving vehicle maybe implemented as a mobile robot, a car, a train, a manned/unmannedaerial vehicle (AV), a ship, or the like.

Referring to FIG. 27, a vehicle or autonomous driving vehicle 100 mayinclude an antenna unit 108, a communication unit 110, a control unit120, a driving unit 140 a, a power supply unit 140 b, a sensor unit 140c, and an autonomous driving unit 140 d. The antenna unit 108 may beconfigured as a part of the communication unit 110. The blocks110/130/140 a to 140 d correspond to the blocks 110/130/140 of FIG. 26,respectively.

The communication unit 110 may transmit and receive signals (e.g., dataand control signals) to and from external devices such as othervehicles, BSs (e.g., gNBs and road side units), and servers. The controlunit 120 may perform various operations by controlling elements of thevehicle or the autonomous driving vehicle 100. The control unit 120 mayinclude an ECU. The driving unit 140 a may enable the vehicle or theautonomous driving vehicle 100 to drive on a road. The driving unit 140a may include an engine, a motor, a powertrain, a wheel, a brake, asteering device, and so on. The power supply unit 140 b may supply powerto the vehicle or the autonomous driving vehicle 100 and include awired/wireless charging circuit, a battery, and so on. The sensor unit140 c may acquire information about a vehicle state, ambient environmentinformation, user information, and so on. The sensor unit 140 c mayinclude an inertial measurement unit (IMU) sensor, a collision sensor, awheel sensor, a speed sensor, a slope sensor, a weight sensor, a headingsensor, a position module, a vehicle forward/backward sensor, a batterysensor, a fuel sensor, a tire sensor, a steering sensor, a temperaturesensor, a humidity sensor, an ultrasonic sensor, an illumination sensor,a pedal position sensor, and so on. The autonomous driving unit 140 dmay implement technology for maintaining a lane on which the vehicle isdriving, technology for automatically adjusting speed, such as adaptivecruise control, technology for autonomously driving along a determinedpath, technology for driving by automatically setting a route if adestination is set, and the like.

For example, the communication unit 110 may receive map data, trafficinformation data, and so on from an external server. The autonomousdriving unit 140 d may generate an autonomous driving route and adriving plan from the obtained data. The control unit 120 may controlthe driving unit 140 a such that the vehicle or autonomous drivingvehicle 100 may move along the autonomous driving route according to thedriving plan (e.g., speed/direction control). During autonomous driving,the communication unit 110 may aperiodically/periodically acquire recenttraffic information data from the external server and acquiresurrounding traffic information data from neighboring vehicles. Duringautonomous driving, the sensor unit 140 c may obtain information about avehicle state and/or surrounding environment information. The autonomousdriving unit 140 d may update the autonomous driving route and thedriving plan based on the newly obtained data/information. Thecommunication unit 110 may transfer information about a vehicleposition, the autonomous driving route, and/or the driving plan to theexternal server. The external server may predict traffic informationdata using AI technology based on the information collected fromvehicles or autonomous driving vehicles and provide the predictedtraffic information data to the vehicles or the autonomous drivingvehicles.

FIG. 28 illustrates a signal processing circuit for Tx signals.

Referring to FIG. 28, a signal processing circuit 1000 may include ascrambler 1010, a modulator 1020, a layer mapper 1030, a precoder 1040,a resource mapper 1050, and a signal generator 1060. Theoperations/functions shown in FIG. 25 may be performed by the processors102 and 202 and/or the transceivers 106 and 206 shown in FIG. 25,without being limited thereto. Hardware elements shown in FIG. 23 may beimplemented by the processors 102 and 202 and/or the transceivers 106and 206 shown in FIG. 25. For example, the blocks 1010 to 1060 may beimplemented by the processors 102 and 202. In addition, the blocks 1010to 1050 may be implemented by the processors 102 and 202 shown in FIG.25, and the block 1060 may be implemented by the transceivers 106 and206 shown in FIG. 25.

The codeword may be converted into a radio signal (or a radio frequency(RF) signal) through the signal processing circuit 1000 shown in FIG.28. Here, the codeword may be a coded bit sequence of an informationblock. The information block may include a transmission (Tx) block(e.g., UL-SCH transmission block, and/or DL-SCH transmission block). Theradio signal may be transmitted through various physical channels (e.g.,PUSCH, and PDSCH).

In more detail, the codeword may be converted into a bit sequencescrambled by the scrambler 1010. The scramble sequence used for suchscrambling may be generated based on an initialization value, and theinitialization value may include ID information of a wireless device,etc. The scrambled bit-sequence may be modulated into a modulated symbolsequence by the demodulator 1020. The modulation scheme may includepi/2-BPSK (pi/2-Binary Phase Shift Keying), m-PSK (m-Phase ShiftKeying), m-QAM (m-Quadrature Amplitude Modulation), etc. The complexmodulated symbol sequence may be mapped to one or more transmission (Tx)layers by the layer mapper 1030. Modulated symbols of the respective Txlayers may be mapped (precoded) to the corresponding antenna port(s) bythe precoder 1040. The output value (z) of the precoder 1040 may beobtained by multiplying the output value (y) of the layer mapper 1030 bythe (N×M) precoding matrix (W). In this case, N is the number of antennaports, and M is the number of Tx layers. In this case, the precoder 1040may perform precoding after transform precoding (e.g., DFT transform) isperformed on the complex modulated symbols. In this case, the precoder1040 may perform precoding without performing transform precoding.

The resource mapper 1050 may map the modulated symbols of the respectiveantenna ports to time-frequency resources. The time-frequency resourcesmay include a plurality of symbols (e.g., CP-OFDMA symbol andDFT-s-OFDMA symbol) in the time domain, and may include a plurality ofsubcarriers in the frequency domain. The signal generator 1060 maygenerate radio signals from the mapped modulated symbols, and thegenerated radio signals may be transferred to other devices through therespective antennas. To this end, the signal generator 1060 may includean inverse fast Fourier transform (IFFT) module, a cyclic prefix (CP)inserter, a digital-to-analog converter (DAC), a frequency uplinkconverter, etc.

The signal processing steps for reception (Rx) signals in the wirelessdevice may be arranged in the reverse order of the signal processingsteps 1010 to 1060 shown in FIG. 28. For example, the wireless devices100 and 200 (shown in FIG. 26) may receive radio signals from theoutside through the antenna ports/transceivers. The received radiosignals may be converted into a baseband signal through a signalrestorer. To this end, the signal restorer may include a frequencydownlink converter, an analog-to-digital converter (ADC), a CP remover,and a fast Fourier transform (FFT) module. Thereafter, the basebandsignal may be restored to the codeword after passing through theresource demapper process, the postcoding process, the demodulationprocess, and the descrambling process. The codeword may be restored toan original information block through decoding. Therefore, the signalprocessing circuit (not shown) for Rx signals may include a signalrestorer, a resource demapper, a postcoder, a demodulator, adescrambler, and a decoder.

The embodiments of the present disclosure described herein below arecombinations of elements and features of the present disclosure. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent disclosure may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent disclosure may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It will beobvious to those skilled in the art that claims that are not explicitlycited in each other in the appended claims may be presented incombination as an embodiment of the present disclosure or included as anew claim by a subsequent amendment after the application is filed.

In the present disclosure, a specific operation described as performedby the BS may be performed by an upper node of the BS in some cases.Namely, it is apparent that, in a network comprised of a plurality ofnetwork nodes including a BS, various operations performed forcommunication with an MS may be performed by the BS, or network nodesother than the BS. The term ‘BS’ may be replaced with the term ‘fixedstation’, ‘Node B’, ‘enhanced Node B (eNode B or eNB)’, ‘access point’,etc.

Those skilled in the art will appreciate that the present disclosure maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent disclosure. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of thedisclosure should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

While the method and apparatus for measuring CSI in an unlicensed bandhave been described above in the context of being applied to a 5G NewRATsystem, they are applicable to various wireless communication systemsother than the 5G NewRAT system.

1. A method of measuring channel state information (CSI) in anunlicensed band by a user equipment (UE), the method comprising:receiving at least one channel state information-reference signal(CSI-RS) via at least one of a plurality of listen-before-talk (LBT)subbands for transmission of a plurality of CSI-RSs in one transmissionopportunity (TxOP) duration; determining a measurement purpose of eachof the at least one CSI-RS; and measuring CSI based on the determinedmeasurement purpose of each of the at least one CSI-RS, wherein thedetermination of a measurement purpose of each of the at least oneCSI-RS comprises determining whether each of the at least one CSI-RS isa CSI-RS for interference measurement or a CSI-RS for signalmeasurement.
 2. The method according to claim 1, wherein based on the atleast one CSI-RS including none of the CSI-RS for interferencemeasurement and the CSI-RS for signal measurement, CSI is not measured.3. The method according to claim 1, further comprising receivinginformation for measuring one of the CSI-RS for interference measurementand the CSI-RS for signal measurement, wherein the measurement of CSIcomprises measuring the CSI based on the at least one CSI-RS being theone CSI-RS or not measuring the CSI based on the at least one CSI-RS notbeing the one CSI-RS.
 4. The method according to claim 1, wherein theone TxOP duration is a TxOP duration closest to a time of measuring theCSI among a plurality of TxOP durations.
 5. The method according toclaim 1, wherein the at least one CSI-RS is a non-zero-power (NZP)CSI-RS.
 6. The method according to claim 5, wherein a resource regionfor a zero-power (ZP) CSI-RS is identical to a resource region for theNZP CSI-RS.
 7. The method according to claim 1, wherein the UE iscommunicable with at least one of another UE, a network, a base station(BS), or an autonomous driving vehicle.
 8. A user equipment (UE) formeasuring channel state information (CSI) in an unlicensed band, the UEcomprising: at least one transceiver; at least one processor; and atleast one memory operably connected to the at least one processor andconfigured to store instructions that, when executed, cause the at leastone processor to perform operations comprising: receiving, through theat least one transceiver, at least one channel stateinformation-reference signal (CSI-RS) in at least one of a plurality oflisten-before-talk (LBT) subbands for transmission of a plurality ofCSI-RSs in one transmission opportunity (TxOP) duration; determining ameasurement purpose of each of the at least one CSI-RS; and measuringCSI based on the determined measurement purpose of each of the at leastone CSI-RS, and wherein the determination of a measurement purpose ofeach of the at least one CSI-RS comprises determining whether each ofthe at least one CSI-RS is a CSI-RS for interference measurement or aCSI-RS for signal measurement.
 9. The UE according to claim 8, whereinbased on the at least one CSI-RS including none of the CSI-RS forinterference measurement and the CSI-RS for signal measurement, CSI isnot measured.
 10. The UE according to claim 8, wherein the specificoperations further include receiving information for measuring one ofthe CSI-RS for interference measurement and the CSI-RS for signalmeasurement, wherein the measurement of CSI comprises measuring the CSIbased on the at least one CSI-RS being the one CSI-RS or not measuringthe CSI based on the at least one CSI-RS not being the one CSI-RS. 11.The UE according to claim 8, wherein the one TxOP duration is a TxOPduration closest to a time of measuring the CSI among a plurality ofTxOP durations.
 12. The UE according to claim 8, wherein the at leastone CSI-RS is a non-zero-power (NZP) CSI-RS.
 13. The UE according toclaim 12, wherein a resource area for a zero-power (ZP) CSI-RS isidentical to a resource area for the NZP CSI-RS.
 14. The UE according toclaim 8, wherein the UE is communicable with at least one of another UE,a network, a base station (BS), or an autonomous driving vehicle.
 15. Anapparatus for measuring channel state information (CSI) in an unlicensedband, the apparatus comprising: at least one processor; and at least onememory operatively coupled to the at least one processor and storinginstructions which when executed, cause the at least one processor toperform specific operations, wherein the specific operations include:receiving, through the at least one transceiver, at least one channelstate information-reference signal (CSI-RS) in at least one of aplurality of listen-before-talk (LBT) subbands for transmission of aplurality of CSI-RSs in one transmission opportunity (TxOP) duration;determining a measurement purpose of each of the at least one CSI-RS;and measuring CSI based on the determined measurement purpose of each ofthe at least one CSI-RS, and wherein the determination of a measurementpurpose of each of the at least one CSI-RS comprises determining whethereach of the at least one CSI-RS is a CSI-RS for interference measurementor a CSI-RS for signal measurement.